Method and system for making light-blocking articles

ABSTRACT

A foamed, opacifying element having a target light blocking value (LBV T ) and a target porous substrate is prepared by determining the light blocking value (LBV S ) of the target porous substrate; calculating the LBV T-S  difference; choosing a foamable aqueous composition; determining a dry coating weight for the chosen foamable aqueous composition (when foamed); and using the dry coating weight to form the single dry opacifying layer as the only layer disposed on the target porous substrate, such that the single dry opacifying layer has light blocking value that is equal to LBV T-S , ±10%. The chosen foamable aqueous composition comprises the essential components (a) through (e) described herein. The desired foamable aqueous composition can be chosen from a set of similar compositions to achieve the desired LBV T  with the noted target porous substrate using suitable mathematical formula relating dry coating weight to light blocking value and a suitable data processor.

RELATED APPLICATIONS

Reference is made to the following copending and commonly assignedpatent applications:

U.S. Ser. No. 15/144,893, filed May 3, 2016, titled “FOAMED, OPACIFYINGELEMENTS,” by Brick et al., that is a continuation-in-part of commonlyassigned U.S. Ser. No. 14/730,280, filed Jun. 4, 2015, now abandoned.

U.S. Ser. No. 15/144,875, filed May 3, 2016, titled “FOAMED AQUEOUSCOMPOSITION,” by Pyszczek et al., recently allowed, that is acontinuation-in-part of commonly assigned U.S. Ser. No. 14/730,269,filed Jun. 4, 2015, now abandoned;

U.S. Ser. No. 15/144,911, filed May 3, 2016, titled “METHOD OF MAKINGFOAMED, OPACIFYING ELEMENTS,” by Brick et al., that is acontinuation-in-part of commonly assigned U.S. Ser. No. 14/730,280,filed Jun. 4, 2015, now abandoned;

U.S. Ser. No. 15/239,915, filed Aug. 18, 2016, titled “FORMABLE ANDFOAMED AQUEOUS COMPOSITIONS,” by Pyszczek et al.;

U.S. Ser. No. 15/239,938, filed Aug. 18, 2016, titled “LIGHT-BLOCKINGARTICLES WITH HIGH OPACIFYING LAYER,” by Nair et al.; and

U.S. Ser. No. 15/239,978, filed Aug. 18, 2016, titled “METHOD OF MAKINGLIGHT-BLOCKING HIGH OPACITY ARTICLES,” by Nair et al.;

the disclosures of all of which applications are incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates to a method and system for providing dry foamed,opacifying elements that are specifically designed to have a targetlight blocking value (LBV_(T)). Such articles are provided using certainstructural and optical parameters such as a target porous substratehaving an inherent light blocking value (LBV_(S)) and a designed coatingweight of a chosen foamed aqueous composition so that the LBV_(T) isachieved.

BACKGROUND OF THE INVENTION

In general, when light strikes a surface, some of it may be reflected,some absorbed, some scattered, and the rest transmitted. Reflection canbe diffuse, such as light reflecting off a rough surface such as a whitewall, in all directions, or specular, as in light reflecting off amirror at a definite angle. An opaque substance transmits almost nolight, and therefore reflects, scatters, or absorbs all of it. Bothmirrors and carbon black are opaque. Opacity depends on the frequency ofthe light being considered. “Blackout” or light blocking materialstypically refer to coated layers in articles that are substantiallyimpermeable to light such as visible or UV radiation. Thus, when ablackout material such as a blackout curtain is hung over a window, itgenerally blocks substantially all external light from entering the roomthrough that window. Blackout materials are suitable as curtains andshades for domestic use, for institutional use in hospitals and nursinghomes, as well as for use in commercial establishments such as hotels,movie theaters, and aircraft windows where the option of excluding lightcan be desirable.

Light blocking articles such as the blackout curtains can be comprisedof a fabric (porous) substrate coated with more than one layer of afoamed latex composition. There is a desire for these curtains, inaddition to blocking transmitted light, to have a light color (hue)facing the environment when an activity needs illumination so as tominimize the amount of artificial lighting needed to perform theactivity. An example is when the function of the blackout material is toseparate two areas of activity where one or both areas can beartificially lit at the same time. However, more often than not, thefunction of a blackout curtain is to prevent sunlight from entering aroom through a building window. It can also be desirable for the color(hue) of the back side to match the external décor of the building.

Light colored blackout curtains can be made by coating a fabric withlight colored foams containing light scattering pigments such astitanium dioxide or clays. However, very thick foam coatings will beneeded to create blackout curtains through which the sun is not visiblein a darkened room using only these pigments. One method that is used toreduce the weight of such blackout materials is to sandwich alight-absorbing, foamed black or grey pigment, such as carbon blacklayer between two light scattering, white pigment-containing layers.

When an electromagnetic radiation blocking coating has, as it oftendoes, a strongly light absorbing material containing black pigments suchas carbon black, between two reflective layers, it has at least twodistinct problems. First, such materials require three separate coatingoperations that reduce manufacturing productivity and increase unitcosts. Secondly, carbon black in the light absorbing middle layer canbecome “fugitive” (or non-enclosed) from some puncture or tear occurringduring sewing or laundering, and soil other layers such as thereflective layers, which is highly objectionable. Additionally, thestitches generated in the materials during sewing can cause the fugitivecarbon from the light absorbing layer to spread over a larger areathereby increasing the area of objectionable shading of the lightcolored surface.

U.S. Pat. No. 7,754,409 (Nair et al.), U.S. Pat. No. 7,887,984 (Nair etal.), U.S. Pat. No. 8,252,414 (Putnam et al.), and U.S. Pat. No.8,329,783 (Nair et al.) describe porous polymer particles that are madeby a multiple emulsion process, wherein the multiple emulsion processprovides formation of individual porous particles comprising acontinuous polymer phase and multiple discrete internal pores, and suchindividual porous particles are dispersed in an external aqueous phase.The described Evaporative Limited Coalescence (ELC) process is used tocontrol the particle size and distribution while a hydrocolloid isincorporated to stabilize the inner emulsion of the multiple emulsionthat provides the template for generating the pores in the porousparticles.

U.S. Patent Application Publication 2015/0234098 (Lofftus et al.)describes improved articles that are designed with an opacifying layerthat is capable of blocking predetermined electromagnetic radiation. Theopacifying layer is disposed on a substrate that can be composed of anysuitable material and a porous or non-porous underlying layer can beincorporated between the substrate and the opacifying layer. While thesearticles have numerous advantages and represent an important advance inthe art, there is a need for further improvement in providing opacifyingarticles that are lighter in weight; and that have improved flexibility,good “hand,” while maintaining light coloration of the surfaces facingan observer without losing reflectivity, and light-absorptiveproperties; launderability; and minimizing dark opacifying agentsgetting out into the environment upon stitching and handling.

An improvement in this art is provided by the foamed aqueouscompositions described and claimed in recently allowed U.S. Ser. No.15/144,875 (noted above) in which very small amounts of opacifyingcolorants can be incorporated into porous particles, and the resultingcomposition has a foam density of at least 0.1 g/cm³.

While the noted foamed compositions and foamed, opacifying elementsdescribed in the previous commonly assigned patent applications providean advance in the art, there is continued need for improvements. Thosefoamed, opacifying elements were designed by experimentation withvarious porous substrates, foamed aqueous compositions, and coatingweights.

However, it would be desirable to have a means for designing foamed,opacifying elements using a chosen target porous substrate and a chosenfoamed aqueous composition to achieve a target (or tailored) lightblocking value that may depend upon various compositional andmanufacturing factors as well as economic or aesthetic values. In otherwords, it would be desirable to have a way to design such foamed,opacifying elements to satisfy a customer's needs for light blocking,costs, or fabric properties such as weight, hand, and feel.

SUMMARY OF THE INVENTION

The present invention provides a method for providing a foamed,opacifying element having a target light blocking value (LBV_(T)) andcomprising a target porous substrate having a first supporting side andan opposing second supporting side, the method comprising:

choosing a target porous substrate;

choosing a target light blocking value (LBV_(T));

determining a light blocking value (LBV_(S)) of the target poroussubstrate;

calculating LBV_(T-S) as a difference between LBV_(T) and LBV_(S);

choosing a foamable aqueous composition;

using a mathematical formula to obtain a dry coating weight for a singledry opacifying layer derived from the chosen foamable aqueouscomposition; and

using the dry coating weight to form the single dry opacifying layer asthe only layer disposed on the first supporting side of the targetporous substrate, such that the single dry opacifying layer has lightblocking value that is equal to LBV_(T-S), ±10%,

wherein the chosen foamable aqueous composition has at least 35% solidsand up to and including 70% solids, and comprises:

(a) at least 0.05 weight % and up to and including 15 weight % of porousparticles, each porous particle comprising a continuous polymeric phaseand a first set of discrete pores dispersed within the continuouspolymeric phase, the porous particles having a mode particle size of atleast 2 μm and up to and including 50 μm and a porosity of at least 20volume % and up to and including 70 volume %, and the continuouspolymeric phase having a glass transition temperature greater than 80°C. and comprising a polymer having a viscosity of at least 80centipoises and up to and including 500 centipoises at a shear rate of100 sec⁻¹ in ethyl acetate at a concentration of 20 weight % at 25° C.,

(b) at least 20 weight % of a binder material;

(c) at least 0.0001 weight % of one or more additives comprising atleast one surfactant;

(d) water; and

(e) at least 0.001 weight % of an opacifying colorant different from allof the one or more (c) additives, which opacifying colorant absorbspredetermined electromagnetic radiation,

all amounts being based on the total weight of the chosen foamableaqueous composition, and wherein the chosen foamable aqueous compositioncan be foamed to provide a foamed aqueous composition having a foamdensity of at least 0.1 g/cm³ and up to and including 0.5 g/cm³.

This invention also provides a system for providing a foamed, opacifyingelement having a target light blocking value (LBV_(T)), comprising:

(A) a set of foamable aqueous compositions, each of the foamable aqueouscompositions independently having at least 35% solids and up to andincluding 70% solids, and independently comprising:

-   -   (a) at least 0.05 weight % and up to and including 15 weight %        of porous particles, each porous particle comprising a        continuous polymeric phase and a first set of discrete pores        dispersed within the continuous polymeric phase, the porous        particles having a mode particle size of at least 2 μm and up to        and including 50 μm and a porosity of at least 20 volume % and        up to and including 70 volume %, and the continuous polymeric        phase having a glass transition temperature greater than 80° C.        and comprising a polymer having a viscosity of at least 80        centipoises and up to and including 500 centipoises at a shear        rate of 100 see in ethyl acetate at a concentration of 20 weight        % at 25° C.,    -   (b) at least 20 weight % of a binder material;    -   (c) at least 0.0001 weight % of one or more additives comprising        at least one surfactant;    -   (d) water; and    -   (e) at least 0.001 weight % of an opacifying colorant different        from all of the one or more (c) additives, which opacifying        colorant absorbs predetermined electromagnetic radiation,    -   all amounts being based on the total weight of the foamable        aqueous composition, and wherein each of the foamable aqueous        compositions can be foamed to provide a foamed aqueous        composition having a foam density of at least 0.1 g/cm³ and up        to and including 0.5 g/cm³;

(B) a set of mathematical formulae associated with the set of foamableaqueous compositions, wherein the set of mathematical formulae relatecoating weight of the respective foamable aqueous compositions torespective light blocking values; and

(C) a data processor configured to perform a method for generating thefoamed, opacifying element having the target light blocking value(LBV_(T)), the method comprising:

-   -   choosing a target porous substrate having a first supporting        side;    -   choosing a target light blocking value (LVB_(T));    -   determining a light blocking value (LBV_(S)) of the target        porous substrate;    -   calculating LBV_(T-S) as a difference between LBV_(T) and        LBV_(S);    -   choosing a foamable aqueous composition;    -   using a mathematical formula to obtain a dry coating weight for        a single dry opacifying layer derived from the chosen foamable        aqueous composition; and    -   using the dry coating weight to form the single dry opacifying        layer as the only layer disposed on the first supporting side of        the target porous substrate, such that the single dry opacifying        layer has a light blocking value that is equal to LBV_(T-S),        ±10%.

The present invention provides a means for taking the specific desiresand specifications of a customer and making foamed, opacifying elementshaving desired overall light blocking capacity. Such elements can bedesigned with predetermined target porous substrates and optimal drythickness of a single dry opacifying layer to meet a target lightblocking value (LBV_(T)) while taking into account various aesthetic oreconomic values. For example, for a given target porous substrate, afoamable aqueous composition (and corresponding foamed aqueouscomposition) can be chosen, and a specific coating weight can bedetermined using appropriate mathematical formulae and processors toachieve the desired LPV_(T) no matter what the weight, porosity, orcolor of the target porous substrate. Thus, a heavier-weight targetporous substrate with its greater inherent porous substrate lightblocking contribution may require a thinner dry opacifying layer while alighter-weight porous substrate may require a thicker dry opacifyinglayer. Such design choices are not possible using the technology of theprior art since the prior art dry opacifying layers are generally fixedas a middle carbon-containing, light-blocking layer between two outerprotective layers to mask the dark color of this middle opacifyinglayer.

Thus, a single-layer foamed, opacifying element can be designedaccording to the present invention to meet desired economic or aestheticvalues, for example to provide (1) economic savings by coating only therequired amount of foamable (or foamed) aqueous composition in the dryopacifying layer, (2) or a more luxurious feel to a lighter-weightporous substrate by coating a heavier or thicker dry opacifying layer.The various desired factors can be carefully balanced to achieve acustomer's needs.

Alternatively, a foamable aqueous composition (and corresponding foamedaqueous composition) can be designed to impart a predetermined or targetlight blocking value (LBV_(T)) at a specified thickness (or coatingweight) of the resulting dry opacifying layer. With routineexperimentation, one skilled in the art can determine a relationshipbetween LBV_(T) and dry coating weight of the dry opacifying layer andthereby readily design foamed, opacifying elements with any desired dryweight, material cost, light blocking value, and tactile feel. Theseexperimental data can be formulated as mathematical formulae or put intoa look-up table (LUT) that can be readily used or consulted for a givenset of conditions and factors to provide a set of dry coating weightsfor a set of possible foamable aqueous compositions. Further details ofthis method and system for using it are provided below.

The foamed, opacifying elements prepared according to the presentinvention comprise a single dry opacifying layer that can also haveantimicrobial and flame retardant properties as well as opacifyingproperties and other optical effects such as color variations.

DETAILED DESCRIPTION OF THE INVENTION

The following discussion is directed to various embodiments of thepresent invention and while some embodiments can be desirable forspecific uses, the disclosed embodiments should not be interpreted orotherwise considered be limit the scope of the present invention, asclaimed below. In addition, one skilled in the art will understand thatthe following disclosure has broader application than is explicitlydescribed for any specific embodiment.

Definitions

As used herein to define various components of the foamed aqueouscomposition and foamable aqueous composition, or materials used toprepare the porous particles, unless otherwise indicated, the singularforms “a,” “an,” and “the” are intended to include one or more of thecomponents (that is, including plurality referents).

Each term that is not explicitly defined in the present application isto be understood to have a meaning that is commonly accepted by thoseskilled in the art. If the construction of a term would render itmeaningless or essentially meaningless in its context, the termdefinition should be taken from a standard dictionary.

The use of numerical values in the various ranges specified herein,unless otherwise expressly indicated otherwise, are considered to beapproximations as though the minimum and maximum values within thestated ranges were both preceded by the word “about.” In this manner,slight variations above and below the stated ranges can be used toachieve substantially the same results as the values within the ranges.In addition, the disclosure of these ranges is intended as a continuousrange including every value between the minimum and maximum values.

Unless otherwise indicated, the terms “foamed, opacifying element,”“element,” and “article” are intended to refer to the same material.

The terms “porous particle” and “porous particles” are used herein,unless otherwise indicated, to refer to porous organic polymericmaterials useful in the foamable aqueous compositions, foamed aqueouscompositions, and foamed opacifying elements prepared according to thepresent invention. The porous particles generally comprise a solidcontinuous polymeric phase having an external particle surface anddiscrete pores dispersed within the continuous polymeric phase. Thecontinuous polymeric phase also can be chemically crosslinked orelastomeric in nature, or both chemically crosslinked and elastomeric innature.

The continuous polymeric phase of the porous particles generally has thesame composition throughout that solid phase. That is, the continuouspolymeric phase is generally uniform in composition including anyadditives (for example, colorants) that can be incorporated therein. Inaddition, if mixtures of polymers are used in the continuous polymericphase, generally those mixtures also are dispersed uniformly throughout.

As used in this disclosure, the term “isolated from each other” refersto the different (distinct) pores of same or different sizes that areseparated from each other by some of the continuous polymeric phase, andsuch pores are not generally interconnected.

The terms “first discrete pore” and “second discrete pore” refer todistinct sets of isolated pores in the porous particles. These first andsecond discrete pores can refer to distinct individual pores, or in mostembodiments, they refer to distinct sets of pores. Each distinct set ofpores includes a plurality of pores, each of which pores is isolatedfrom others pores in the set of pores, and the pores of each set ofpores are isolated from all other pores of the other sets of pores inthe porous particle. Each set of pores can have the same mode averagesize or both sets can have the same mode average size. The word“discrete” is also used to define different droplets of the first andsecond aqueous phases when they are suspended in the oil (solvent) phase(described below).

The porous particles can include “micro,” “meso,” and “macro” discretepores, which according to the International Union of Pure and AppliedChemistry, are the classifications recommended for discrete pore sizesof less than 2 nm, from 2 nm to 50 nm, and greater than 50 nm,respectively. Thus, while the porous particles can include closeddiscrete pores of all sizes and shapes (that is, closed discrete poresentirely within the continuous polymeric phase) providing a suitablevolume in each discrete pore, macro discrete pores are particularlyuseful. While there can be open macro pores on the surface of the porousparticle, such open pores are not desirable and can be present only byaccident. The size of the porous particle, the formulation, andmanufacturing conditions are the primary controlling factors fordiscrete pore size. However, typically the discrete pores independentlyhave an average size of at least 100 nm and up to and including 7,000nm, or more likely at least 200 nm and up to and including 2,000 nm.Whatever the size of the discrete pores, they are generally distributedrandomly throughout the continuous polymeric phase. If desired, thediscrete pores can be grouped predominantly in one part (for example,“core” or “shell”) of the porous particles.

The porous particles used in this invention generally have a porosity ofat least 20 volume % and up to and including 70 volume %, or likely atleast 40 volume % and up to and including 65 volume %, or more typicallyat least 45 volume % and up to an including 60 volume %, all based onthe total porous particle volume. Porosity can be measured by the knownmercury intrusion technique.

“Opacity” is a measured parameter of a foamed, opacifying elementprepared according to the present invention that characterizes theextent of transmission of electromagnetic radiation such as visiblelight. A greater light blocking value indicates a more efficientblocking (hiding) of predetermined radiation (as described below). Inthe present invention, the “opacity” of a material is determined bymeasuring the light blocking value (LBV), as exemplified below, whichdetermines the extent to which the impinging radiation or light isblocked by the material. The higher the LBV, the greater the lightblocking ability exhibited by the material.

The light blocking ability of a foamed, opacifying element, for example,a target light blocking value (LVB_(T)), in transmitted light, can bedetermined using a custom-built apparatus consisting of a fiber opticXenon light source, a computer controlled translational stage and anoptical photometer. In this procedure, the fiber optic Xenon lightsource was positioned 10 mm above the surface of the foamed, opacifyingelement. A photo detector was placed on the opposite side of the foamed,opacifying element directly across from the fiber optic Xenon lightsource, in order to quantify the amount of light that passed through thefoamed, opacifying element. The light blocking value of each foamed,opacifying element was calculated by comparing the light intensity (I)that passed through the foamed, opacifying element to the lightintensity (I₀) that reaches the photo detector from the fiber opticXenon light source over the same distance when no foamed, opacifyingelement is present, and using the equation:

−log₁₀(I/I ₀).

Each target porous substrate that can be used in the present inventionhas an inherent light blocking value (LBV_(S)). Such values can bedetermined by the same manner as described above for determined thelight blocking value of a foamed, opacifying element.

A dry opacifying layer obtained using the present invention can have alight blocking value that can be identified as LBV_(L), and can be thecalculated difference between a target light blocking value LBV_(T) andLBV_(S), or LBV_(T-S).

The luminous reflectance (or brightness) of each foamed, opacifyingelement was determined by first measuring the spectral reflectance inthe 400-700 nm wavelength range using a Hunter Labs UltraScan XEcolorimeter equipped with an integrating sphere and a pulsed Xenon lightsource. A light trap and a standard white tile were used to fix thereflectance range from 0 to 100%. The X, Y, and Z tristimulus values ofeach dry opacifying layer were also determined and used in conjunctionwith the CIELab color space (standard D65 illuminant) to calculatespecific values for the lightness (L*), red-green character (a*), andyellow-blue character (b*) of each dry opacifying layer. The Ytristimulus value was used as a measure of the luminous reflectance or“brightness” of each sample.

Glass transition temperatures of the organic polymers used to preparethe continuous polymeric phase can be measured using DifferentialScanning calorimetry (DSC) using known procedures. For many commerciallyavailable organic polymers, the glass transition temperatures are knownfrom the suppliers.

Polymer viscosity (in centipoises) comprising the continuous polymericphase can be measured in ethyl acetate at concentration of 20 weight %of the polymer at 25° C. in an Anton Parr MCR 301 stress rheometer in acoquette using steady shear sweeps. Shear rate at 100 sec⁻¹ wascalculated from the resulting graphical plot of viscosity vs. shearrate.

CIELAB L*, a*, and b* values described herein have the known definitionsaccording to CIE 1976 color space or later known versions of color spaceand were calculated assuming a standard D65 illuminant. The Ytristimulus value of the X, Y, and Z tristimulus values was used as ameasure of the luminous reflectance or “brightness” of a dry opacifyinglayer.

Uses

The foamable aqueous compositions and foamed aqueous compositionsdescribed herein can be used to prepare foamed, opacifying elements thatin turn can be useful as radiation (light and heat) blocking materialsas for example, as blackout curtains, carpets, banners, and windowshades for airplanes, labels, projection screens, textile fabrics, andpackaging materials. The foamed, opacifying elements can also bedesigned to provide improved sound and heat blocking properties. Theterm “blackout curtain” is intended to include but not limited to,window curtains, shades for all purposes, draperies, room dividers,privacy curtains, and cubicle curtains suitable for various environmentsand structures. The foamed, opacifying elements prepared according tothe present invention can exhibit blackout (light blocking) propertiesand can optionally have an opaque printable surface able to accept inkusing in screen printing, inkjet printing, or other printing processes.Thus, one can provide opposing printable surfaces in such materials(elements) with the same light blocking capacity as if only one side wasprinted, with no printed image on one side showing through the otherside.

Foamable Aqueous Compositions

The foamable aqueous compositions useful in the present invention can besuitably aerated to provide foamed aqueous compositions. The foamableaqueous compositions used in the present invention have five essentialcomponents, that is, only five components needed to obtain theproperties of the foamed, opacifying element described herein, all ofwhich are described below: (a) porous particles; (b) a binder material;(c) one or more additives comprising at least one surfactant; (d) water;and (e) an opacifying colorant different from all of the compounds ofcomponent (c), which opacifying colorant absorbs “predeterminedelectromagnetic radiation” (generally UV to near-IR, for example,absorbing the radiation of all wavelengths of from 350 nm to 800 nm orfrom 350 nm to and including 700 nm). Optional (non-essential)components that can be included are also described below.

The foamable aqueous composition used according to this inventiongenerally has at least 35% and up to and including 70% solids, or moreparticularly at least 40% and up to and including 60% solids.

Porous Particles:

Porous particles used in the present invention containing discrete pores(or compartments) are used in each dry opacifying layer and they aregenerally prepared, as described below, using one or more water-in-oilemulsions in combination with an aqueous suspension process, such as inthe Evaporative Limited Coalescence (ELC) process. The details for thepreparation of the porous particles are provided, for example, in U.S.Pat. No. 8,110,628 (Nair et al.), U.S. Pat. No. 8,703,834 (Nair), U.S.Pat. No. 7,754,409 (Nair et al.), U.S. Pat. No. 7,887,984 (Nair et al.),U.S. Pat. No. 8,329,783 (Nair et al.), and U.S. Pat. No. 8,252,414(Putnam et al.), the disclosures of all of which are incorporated hereinby reference. Thus, the porous particles are generally polymeric andorganic in nature (that is, the continuous polymeric phase is polymericand organic in nature) and non-porous particles (having less than 5%porosity) are excluded. Inorganic particles can be present on the outersurface as noted below.

The porous particles are composed of a continuous polymeric phasederived from one or more organic polymers that are chosen so that thecontinuous polymeric phase has a glass transition temperature (T_(g)) ofgreater than 80° C., or more typically of at least 100° C. and up to andincluding 180° C., or more likely at least 110° C. and up to andincluding 170° C. as determined using Differential Scanning calorimetry.Polymers having a T_(g) that is greater than 200° C. are typically lessuseful in the continuous polymeric phase.

In addition, the continuous polymeric phase comprises one or morepolymers each of which has a viscosity of at least 80 centipoises and upto and including 500 centipoises at a shear rate of 100 sec⁻¹ asmeasured in ethyl acetate at a concentration of 20 weight % at 25° C.This feature is important to optimize the preparation of porousparticles used in the practice of this invention so that the preparedporous particles have a narrow particle size distribution and highporosity.

For example, the continuous polymeric phase can comprise one or morepolymers having the properties noted above, wherein generally at least70 weight % and up to and including 100 weight % based on the totalpolymer weight in the continuous polymeric phase, is composed of one ormore cellulose polymers (or cellulosic polymers) including but notlimited to, those cellulosic polymers derived from one or more ofcellulose acetate, cellulose butyrate, cellulose acetate butyrate, andcellulose acetate propionate. A polymer derived solely from celluloseacetate butyrate is particularly useful. Mixtures of these cellulosepolymers can also be used if desired, and mixtures comprising a polymerderived from cellulose acetate butyrate as at least 80 weight % of thetotal of cellulose polymers (or of all polymers in the continuouspolymeric phase) are particularly useful mixtures.

In general, the porous particles used in the present invention can havea mode particle size equal to or less than 50 μm, or of at least 2 μmand up to and including 50 μm, or typically of at least 3 μm and up toand including 30 μm or even up to and including 40 μm. Most usefulporous particles can have a mode particle size of at least 3 μm and upto and including 20 μm. Mode particle size represents the mostfrequently occurring diameter for spherical particles and the mostfrequently occurring largest diameter for the non-spherical particles ina particle size distribution histogram.

Pore stabilizing materials such as hydrocolloids can be present withinat least part of the volume of the discrete pores distributed throughoutthe continuous polymeric phase, which pore stabilizing materials aredescribed in patents cited above. In some embodiments, the same porestabilizing material is incorporated in essentially all of the discretepores throughout the entire porous particles. In many embodiments, thepore stabilizing hydrocolloids are selected from the group consisting ofcarboxymethyl cellulose (CMC), a gelatin, a protein or proteinderivative, polyvinyl alcohol and its derivatives, a hydrophilicsynthetic polymer, and a water-soluble microgel.

It can be desired in some embodiments to provide additional stability ofone or more discrete pores in the porous particles during theirformation, by having one or more amphiphilic block copolymers disposedat the interface of the one or more discrete pores and the continuouspolymeric phase. Such materials are “low HLB,” meaning that they have anHLB (hydrophilic-lipophilic balance) value as it is calculated usingknown science, of 6 or less, or even 5 or less. The details of theseamphiphilic polymers and their use in the preparation of the porousparticles are provided in U.S. Pat. No. 9,029,431 (Nair et al.), thedisclosure of which is incorporated herein by reference.

A particularly useful amphiphilic block copolymer useful in suchembodiments comprises poly(ethyleneoxide) and poly(caprolactone) thatcan be represented as PEO-b-PCL. Amphiphilic block copolymers, graftcopolymers and random graft copolymers containing similar components arealso useful.

Such an amphiphilic block copolymer can be present in the porousparticles in an amount of at least 1 weight % and up to and including99.5 weight %, or at least 2 weight % and up to and including 50 weight%, based on total porous particle dry weight.

The porous particles used in this invention can be spherical ornon-spherical depending upon the desired use. In a method used toprepare the porous particles, additives (shape control agents) can beincorporated into the first or second aqueous phases, or in the oil(organic) phase to modify the shape, aspect ratio, or morphology of theporous particles. The shape control agents can be added prior to orafter forming the water-in-oil-in-water emulsion. In either case, theinterface at the oil and second water phase is modified before organicsolvent is removed, resulting in a reduction in sphericity of the porousparticles. The porous particles used in the present invention can alsocomprise surface stabilizing agents, such as colloidal silica or variouspolymers, on the outer surface of each porous particle, in an amount ofat least 0.1 weight %, based on the total dry weight of the porousparticle.

The average size of the discrete pores (or individually isolated andclosed voids or compartments) is described above.

The porous particles can be provided as powders, or as aqueoussuspensions (including water or water with water-miscible organicsolvents such as alcohols). Such powders and aqueous suspensions canalso include surfactants or suspending agents to keep the porousparticles suspended or when rewetting them in an aqueous medium. Auseful surfactant for this purpose, for example is a C₁₂-C₁₄ secondaryalcohol derivative of poly(ethylene oxide) that can be commerciallyavailable as TERGITOL® 15-S-7 (Dow Chemical Corporation). The othercompositional features are described in the incorporated description ofmethods for preparing the porous particles.

The porous particles can be present in the foamable aqueous compositionin an amount of at least 0.05 weight % and up to and including 15 weight%, or typically at least 0.5 weight % and up to and including 10 weight%, based on the total weight of the foamable aqueous composition(including water that is present), particularly when the porousparticles have a mode size of at least 3 μm and up to and including 30μm.

It is known in the art, that typical white inorganic pigments such astitanium dioxide block electromagnetic radiation by light scattering asa result of refractive index differences between the inorganic pigmentparticles and the surroundings influenced by the pigment particle size.Additionally, there is only so much volume that can be filled (0.635 ofrandom close packing of monodispersed spheres) before interstitialcavities form between packed pigment particles.

The light blocking value (or opacity) of a single dry opacifying layer(LBV_(L)) is enhanced by interstitial voids that are formed when theparticle volume concentration (PVC), typically pigment particles such astitanium dioxide, is above a critical level. The sizes of theinterstitial voids for example between the pigment particles are smallerthan the pigment particles themselves and decrease with increasingpolydispersity of such pigment particles. Since the pigment particlesizes are optimized for maximum light scattering when dispersed in apolymeric matrix above the critical PVC, the interstitial voids createdby the pigment particles will be too small to also optimally scatterlight. Crowding occurs when the spacing between pigment particlesdecreases to the point where the light scattering becomes dependent onthe concentration of the pigment particles and the effectiveness ofscattering by the pigment particles is reduced as the pigment loading isincreased. This is known as “dependent scattering,” a phenomenon wherebythe effective scattering diameter, or scattering zones, of pigmentparticles become effectively greater than their actual diameter. Thesescattering zones overlap as the concentration of scattering pigmentparticles increases, reducing scattering efficiency, and resulting inthe crowding effect. Small and large pigment particle size extendershave been used in an attempt to create greater separation between thescattering pigment particles and to reduce the overlap of the scatteringzones to result in greater scattering efficiency and light blockingcapacity (opacity).

Advantageously, for the porous particles used in the present invention,the spacing between the light scattering discrete pores within theporous particles is controlled during the process of forming them and isnot subject to subsequent formulation effects such as dependentscattering effects.

Optimal single dry opacifying layers designed according to the presentinvention comprise: porous particles containing a small amount of anopacifying colorant as described below to enhance the light blockingcapacity of the porous particles (particularly transmitted lightblocking capacity); a binder material to hold the porous particles inplace; and surfactants and other additives including optionally one ormore tinting colorants that can be in other porous particles ordispersed within the binder material. The foamed aqueous compositionused to prepare the single dry opacifying layer comprises foam cellsthat surround the porous particles.

Upon drying the foamed aqueous composition, the large mismatch inrefractive index between the discrete pores of the porous particles inthe single dry opacifying layer and the polymer walls (continuouspolymeric phase), and the dried foam cells, causes incidentelectromagnetic radiation passing through the single dry opacifyinglayer to be scattered by the multiplicity of interfaces and discretepores. The back scattered electromagnetic radiation can again bescattered and returned in the direction of the incident electromagneticradiation thus reducing the attenuation and contributing to theopacifying power and brightness or luminous reflectance of the dryopacifying layer. If a small amount of electromagnetic radiationabsorbing opacifying colorant is present in the porous particles of thedry opacifying layer, for example either in the discrete pores or in thecontinuous polymer phase of the porous particles, the light blockingcapacity of the single dry opacifying layer is increased. This isbecause the multiple scattering of electromagnetic radiation in the dryopacifying layer increases the path length of the electromagneticradiation through the single dry opacifying layer, thereby increasingthe chance that the electromagnetic radiation will encounter theopacifying colorant in the dry opacifying layer and be blocked orabsorbed by it.

A single dry opacifying layer present according to the present inventioncomprises porous particles and a relatively low amount of apredetermined electromagnetic radiation absorbing opacifying colorantsuch as carbon black for creating electromagnetic radiation blockingcoatings and the dry foam cells surrounded by the binder material.Multiple light scattering effects by and among the porous particles andthe surrounding dry foam cells, increase the path of the radiationthrough the single dry opacifying layer. The likelihood of radiationencountering an opacifying colorant is increased by this greater pathlength.

Binder Materials:

The foamable and foamed aqueous compositions used in the presentinvention also comprise one or more binder materials (that can behave asa “matrix” for all of the materials in the compositions and resultingsingle dry opacifying layer) to hold the essential porous particles,additives, opacifying colorants, and any optional materials togetherupon application to the target porous substrate and drying to form asingle dry opacifying layer.

It is particularly useful that the binder material have the followingproperties: (a) it is water-soluble or water-dispersible; (b) it iscapable of forming a stable foamed aqueous composition with theessential and optional components described herein; (c) it is capable ofbeing disposed onto a suitable porous substrate as described below; (d)it does not inhibit the aeration (foaming) process (described below);(e) it is capable of being dried and where desired also crosslinked (orcured); (f) it has good light and heat stability; (g) it is film-formingbut contributes to the flexibility of the foamed, opacifying element andis thus not too brittle, for example having a T_(g) of less than 25° C.

The choice of binder material can also be used to increase thelaundering properties of the resulting foamed opacifying compositions inthe foamed, opacifying elements. In addition, the binder material can beused to provide a supple feel to touch and flexibility especially whendisposed on a porous substrate (for example, a fabric) that is meant forwindow coverings such as draperies. The binder material is useful in thefoamed, opacifying element for binding together and adhering the porousparticles and other materials in the dry foamed composition onto theporous substrate.

The binder material can include one or more organic polymers that arefilm forming and that can be provided as an emulsion, dispersion, or anaqueous solution, and that cumulatively provide the properties notedabove. It can also include polymers that are self-crosslinking orself-curable, or it can include one or more polymers to whichcrosslinking agents are added and are thus curable or capable of beingcrosslinked (or cured) under appropriate conditions.

Thus, if the binder material is crosslinkable (or curable) in thepresence of a suitable crosslinking agent, such crosslinking (or curing)can be activated chemically with heat, radiation, or other known means.A curing or crosslinking agent serves to provide improved insolubilityof the resulting dry foamed composition, cohesive strength, and adhesionto the porous substrate. The curing or crosslinking agent is generally achemical having functional groups capable of reacting with reactivesites in a binder material (such as a functionalized latex polymer)under curing conditions to thereby produce a crosslinked structure.Representative crosslinking agents include but are not limited to,multi-functional aziridines, aldehydes, methylol derivatives, andepoxides.

Useful binder materials include but are not limited, to poly(vinylalcohol), poly(vinyl pyrrolidone), ethylene oxide polymers,polyurethanes, urethane-acrylic copolymers, other acrylic polymers,styrene-acrylic copolymers, vinyl polymers, styrene-butadienecopolymers, acrylonitrile copolymers, polyesters, silicone polymers, ora combination of two or more of these organic polymers. Such bindermaterials are readily available from various commercial sources or canbe prepared using known starting materials and synthetic conditions. Thebinder material can be anionic, cationic or nonionic in net charge. Auseful class of film-forming binder materials includes aqueous latexpolymer dispersions such as acrylic latexes that can be ionic ornonionic colloidal dispersions of acrylate polymers and copolymers. Forexample, useful film-forming aqueous latexes include but are not limitedto, styrene-butadiene latexes, poly(vinyl chloride) and poly(vinylidenechloride) latexes, poly(vinyl pyridine) latexes, poly(acrylonitrile)latexes, and latexes formed from N-methylol acrylamide, butyl acrylate,and ethyl acrylate. Examples of suitable commercially available bindermaterials include those sold by DSM under the trade names NEOREZ®A-1150, NEOCRYL® A-6093, by Dow under the trade name RHOPLEX® NW-1845Kand by BASF under the tradenames BUTOFAN® N S144, and BUTOFAN® NS 222,by Lubrizol under the tradenames HYSTRETCH′ and HYCAR®, and resins soldby Royal Adhesives such as PARANOL® AC-2032.

The binder material generally has a glass transition temperature that isless than 25° C., and more likely equal to or less than 0° C. Glasstransition temperature can be determined using known procedures and suchvalues are already known for many polymers useful as binder materials inthis invention. The binder material desirably has adequate flexibilityand tensile strength in order to maintain integrity upon handling,especially for use with porous textile substrates.

The one or more binder materials can be present in the foamable aqueouscomposition in an amount of at least 20 weight %, or at least 20 weight% and up to and including 60 weight %, or typically at least 30 weight %and up to and including 50 weight %, based on the total foamable aqueouscomposition (that is, the total weight of all components includingwater).

Additives:

The foamable aqueous compositions can include at least 0.0001, or atleast 0.001 weight %, or even at least 0.01 weight %, and up to andincluding 2 weight %, or up to and including 5 weight %, or even up toand including 20 weight %, or even at least and including 30 weight % ofone or more additives comprising at least one surfactant as definedbelow. Other useful additives include but are not limited toplasticizers, inorganic or organic pigments and dyes (for example,pigment or dye colorants different from the opacifying colorantsdescribed below), flame retardants, biocides, fungicides, antimicrobialagents, preservatives, pH buffers, optical brighteners, tintingcolorants, metal particles such as metal platelets or metal flakes,thickeners, and inorganic fillers (such as clays) that are not any ofthe other additive materials or opacifying colorants described below.These amounts refer to the total of all of the one or more additives ina given foamable aqueous composition and are based on the total weightof those compositions (including water). There can be mixtures of eachtype of additive, or mixtures of two or more types of additives in eachof these compositions.

Any of these additives or mixtures thereof, can be present within anylocation of the foamed aqueous composition, including but not limitedto: the continuous polymeric phase; a volume of the first set (or otherset) of discrete pores; or both the first set (or other set) of discretepores and the continuous polymeric phase of the porous particles.Alternatively, the one or more additives can be present within thebinder material alone, or both within the binder material and within theporous particles.

In all embodiments, the (c) additives useful in the present inventionare not the same compounds as the (a) porous particles, (b) bindermaterials, and (d) opacifying colorants as described herein.

As noted above, at least one additive is a surfactant that is defined asa compound that reduces surface tension in a composition. In mostembodiments, this essential surfactant is a foaming agent that functionsto create and enhance foam formation. In many such embodiments, the oneor more (c) additives comprise one or more foaming agents (surfactants)as well as one or more foam stabilizing agents that are also surfaceactive agents that function to structure and stabilize the foam.Examples of useful foaming agents (surfactants) and foam stabilizingdispersing agents include but are not limited to, ammonium stearate,sodium lauryl sulfate, ammonium lauryl sulfate, ammonium sulfosuccinate,disodium stearyl sulfosuccinate, ethoxylated alcohols, ionic, nonionicor anionic agents such as fatty acid soaps or a fatty acid condensationproduct with an alkylene oxide, for example, the condensation product ofethylene oxide with lauryl or oleic acid or an ester of fatty alcoholsand similar materials, many of which can be obtained from variouscommercial sources. Mixtures of foaming agents can be used if desired.

The relative amounts of each of these two types of (c) additives is notcritical as long as the desired function is evident, that is suitablefoaming properties as required to prepare a foamed aqueous compositionaccording to the present invention, and stability of that foamed aqueouscomposition during storage and manufacture of the foamed, opacifyingelements. The optimal amounts of each of these additives can bedetermined by using routine experimentation and the teaching providedherein.

Other useful (c) additives include metal particles that can be obtainedfrom any available commercial source as metal flakes or metal plateletsand in dry form or as a suspension. Such metal flakes or metal plateletsare substantially 2-dimensional particles, having opposing main surfacesor faces separated by a relatively minor thickness dimension. The metalflakes can have a size range of at least 2 μm and up to and including 50μm in main surface equivalent circular diameter (ECD) wherein the ECD isthe diameter of a circle having the same area as the main face. Examplesof useable metal flakes include those available from Ciba SpecialtyChemicals (BASF) such as aluminum flakes that are available as METASHEEN91-0410 in ethyl acetate, and copper flakes that can be obtained fromvarious commercial sources. Further details of useful metal flakes areprovided in Cols. 11-12 of U.S. Pat. No. 8,614,039 (Nair et al.), thedisclosure of which is incorporated herein by reference. The metalparticles described above, and particularly the metal flakes can be inthe foamable aqueous composition in any suitable location but they areparticularly useful when incorporated within the porous particles suchas within the volume of the discrete pores of the porous particles.

Useful biocides (that is, antimicrobial agents or antifungal agents)that can be present as (c) additives include but are not limited to,silver metal (for example, silver particles, platelets, or fibrousstrands) and silver-containing compounds such as silver chelates andsilver salts such as silver sulfate, silver nitrate, silver chloride,silver bromide, silver iodide, silver iodate, silver bromate, silvertungstate, silver phosphate, and silver carboxylates. In addition,copper metal (for example, copper particles, platelets, or fibrousstrands) and copper-containing compounds such as copper chelates andcopper salts can be present as (c) additives for biocidal purposes.Mixtures of any of silver metal, silver-containing compounds, coppermetal, and copper-containing compounds, can also be present and used inthis manner.

It can also be useful to include thickeners as (c) additives in order tomodify the viscosity of the foamable aqueous composition and tostabilize it as long as aeration is not inhibited. A skilled worker canoptimize the viscosity so as to obtain optimal aeration conditions anddesired foam density as described below. Useful thickeners can beutilized to control the rheology of the foamable aqueous compositiondepending upon the method used to form the dry opacifying layer on aporous substrate as described below. Particularly useful rheologymodifiers are RHEOVIS® PU 1214 (BASF) and ACRYSOL® G111 (Dow ChemicalCompany).

Particularly useful (c) additives comprise one or more tinting colorantsthat can be used to provide a specific observable color, coloration, orhue in the resulting foamed, opacifying elements. These materials arenot chosen to provide the opacifying property described below for theopacifying colorants and thus, tinting colorants are intended to bedifferent materials than the opacifying colorants.

Mixtures of tinting colorants can be present in the foamable aqueouscompositions and they can be different in composition and amount fromeach other. The desired coloration or hue can be obtained using specifictinting colorants can be used in combination with opacifying colorant(s)described below to offset or modify the original color of a foamed,opacifying element (without such materials) to provide more whiteness(or brightness) in the final “color” (or coloration). The one or moretinting colorants can be incorporated within the porous particles(either within the volume of discrete pores, within the continuouspolymeric phase, or in both places) or they can be uniformly dispersedwithin the binder material. In some embodiments, a tinting colorant canbe incorporated within the same porous particles that also include anopacifying colorant (as described below). Alternatively, one or moretinting colorants can be present within both the porous particles (in asuitable location) and within the binder material.

In some embodiments, a first population of porous particles describedherein comprising opacifying colorants as described below, and anotherpopulation of porous particles described herein comprising tintingcolorants can be mixed with the first population of porous particles.The two sets of porous particles can comprise the same or differentpolymers in the continuous polymeric phase.

The one or more tinting colorants can be present in the foamable aqueouscomposition in an amount of at least 0.0001 weight %, or more typicallyat least 0.001 weight %, and up to and including 3 weight %, based onthe total weight of the foamable aqueous composition (including water).Tinting colorants can be dyes or organic pigments that are soluble ordispersible in organic solvents and polymers that are used for makingthe porous particles and thus can be included within the oil phase usedto prepare such porous particles. Alternatively, the tinting colorantscan be primarily water-soluble or water-dispersible materials andincluded into an aqueous phase used to prepare the porous particles.

It can also be useful to include one or more optical brighteners as (c)additives to increase the whiteness (brightness or “fluorescent” effect)of the final coloration in the foamed, opacifying element. Opticalbrighteners are sometimes known in the art as “fluorescent whiteners” or“fluorescent brighteners.” In general, such materials are organiccompounds selected from classes of known compounds such as derivativesof stilbene and 4,4′-diaminostilbene (such as bistriazinyl derivative);derivatives of benzene and biphenyl (such as styril derivatives);pyrazolines; derivatives of bis(benzoxazole-2-yl); coumarins;carbostyrils; naphthalimides; s-triazines; and pyridotriazoles. Specificexamples of optical brighteners can be found in various publicationsincluding “Fluorescent Whitening Agents,” Kirk-Othmer Encyclopedia ofChemical Technology, Fourth Edition, volume 11, Wiley & Sons, 1994. Oneof more of such compounds can be present in an amount of at least 0.01weight % and up to and including 2 weight %, all based on the totalweight of the foamable aqueous composition.

When present, one or more optical brighteners can be in one or morelocations in the foamed aqueous composition. For example, an opticalbrightener can be present in the binder material. Alternatively, anoptical brightener can be present within: the continuous polymeric phaseof the porous particles; a volume of the first set (or any other set) ofdiscrete pores in the porous particles; or both in a volume of the firstset (or any other set) of discrete pores and the continuous polymericphase, of the porous particles.

In many useful embodiments, the (c) additives comprise two or morematerials selected from surfactant that is a foaming agent, a foamstabilizing agent, a tinting agent, an optical brightener, flameretardants, an antimicrobial agent, and an inorganic filler (such as aclay).

Water:

Water is the primary solvent used in the foamable aqueous compositionsused according to the present invention. By “primary” is meant that ofthe total weight of solvents, water comprises at least 75 weight %, andmore likely at least 80 weight % and up to and including 100 weight % ofthe total solvent weight. Auxiliary solvents that can be present mustnot adversely affect or harm the other components in the composition,namely the porous particles, binder materials, one or more additives,and opacifying agents. Nor must such auxiliary solvents adversely affectformation of the foamable aqueous composition or its use to prepare afoamed, opacifying element. Such auxiliary solvents can bewater-miscible organic solvents such as alcohols and ketones.

The solvents then, primarily water, comprise at least 30 weight % and upto and including 65 weight %, or typically at least 40 weight % and upto and including 60 weight %, of the total weight of the foamableaqueous composition.

Opacifying Colorants:

The opacifying colorants used in the present invention can be a singlecolorant or chosen from any suitable combination of colorants such thatthe single or multiple colorants form the “opacifying colorant” thatabsorbs predetermined electromagnetic radiation (defined above) toprovide blackout properties (or suitable opacity). Opacifying colorantscan be soluble dyes or pigments or combinations of each or both types ofmaterials. The opacifying colorants are different from all of thecompounds defined above as the (c) additives.

In most embodiments, the one or more opacifying colorants are presentwithin a volume of the first set (or another set) of discrete poreswithin the porous particles, within the continuous polymeric binder ofthe porous particles, or within both the volume of the first set (oranother set) of discrete pores and the continuous polymeric binder ofthe porous particles. This is highly advantageous as the porousparticles can be used to “encapsulate” various opacifying colorants aswell as tinting colorants and other (c) additives so they are keptisolated from the other components of the foamable aqueous compositionand are additionally not exposed to the environment during sewing orupon surface damage of the foamed, opacifying element. However, in someembodiments, it can be useful to incorporate opacifying agents solely oradditionally within the binder material in which the porous particlesare dispersed.

As used herein, an “opacifying colorant” includes one or more colorantmaterials that are chosen, individually or in combination, to providethe blocking of predetermined electromagnetic radiation (as describedabove). While the opacifying colorants can provide some coloration ordesired hue, they are not purposely chosen for the purpose and are thusmaterials that are chosen to be different from the tinting colorantsdescribed above.

Examples of opacifying colorants that can be used individually or incombination include but are not limited to, neutral or black pigments ordyes, a carbon black, black iron oxide, graphite, aniline black,anthraquinone black, and combinations of colored pigments or dyes suchas combinations of two or more cyan, magenta, green, orange, blue, red,and violet dyes. The present invention is not limited to only thespecific opacifying colorants described herein but these are consideredas representative and as suitable guidance for a skilled worker todevise other combinations of opacifying colorants for the desiredabsorption in the predetermined electromagnetic radiation. A carbonblack or a neutral or black pigment or dye (or combination thereof) isparticularly useful as an opacifying colorant, of which there are manytypes available from commercial sources. Combinations of dyes orpigments such as a combination of the subtractive primary coloredpigments (cyan, magenta, and yellow colored pigments) can also be usedto provide a “black” or visually neutral opacifying colorant.

The opacifying colorant can be generally present in the foamable aqueouscomposition in an amount of at least 0.001 weight % and up to andincluding 0.5 weight %, or even at least 0.003 weight % and up to andincluding 0.2 weight %, all based on the total weight of the foamableaqueous composition (including the weight of solvent). These amountsrefer to the total amount of one or a mixture of opacifying colorants.For example, as noted above, an opacifying colorant can comprise acombination of two or more component colorants (such as a combination ofdyes or a combination of pigments) designed in hues and amounts so thatthe combination meets the desired properties described herein.

In particular embodiments, the opacifying colorant is a carbon blackthat is present in an amount of at least 0.003 weight % and up to andincluding 0.2 weight %, based on the total weight of the foamableaqueous composition.

In some embodiments, the opacifying colorants, if in pigment form, aregenerally milled to a fine particle size and then encapsulated withinthe volume of the discrete pores of the porous particles byincorporating the milled pigment within an aqueous phase used in makingthe porous particles. Alternatively, the opacifying colorant can beincorporated within the continuous polymeric phase of the porousparticles by incorporating the opacifying colorant in the oil phase usedin making the porous particles. Such arrangements can be achieved duringthe manufacture of the porous particles using the teaching providedherein and teaching provided in references cited herein.

In some embodiments, it can be useful to incorporate or dispose at least95% (by weight) of the total opacifying colorant (or combination ofcomponent colorants) within the porous particles (either in the volumeof the discrete pores, continuous polymeric phase, or both), and toincorporate the remainder, if any, within the binder material. However,in many embodiments, 100 weight % of the opacifying colorant isincorporated within the porous particles. For example, more than 50weight % of the total opacifying colorant can be disposed orincorporated within the continuous polymeric phase of the porousparticles, and the remainder can be incorporated within the volume ofthe discrete pores.

The opacifying colorants useful in the practice of this invention can beincorporated into the volume of the discrete pores of individual porousparticles for example, by incorporating them in a first water phase toform a water-in-oil emulsion or in the continuous polymeric phase of theindividual porous particles by incorporating them in the oil phase. In aparticular embodiment, an opacifying colorant can be incorporated intothe first aqueous phase in the form of a milled solid particledispersions of the opacifying colorant. Preparation of milled solidparticle dispersions can include combining the opacifying colorantparticles to be reduced in size with a dispersant and a liquid mediumsuch as water or ethyl acetate (when the opacifying colorant isincorporated in the continuous polymeric phase of the particle) in whichthe porous particles are to be dispersed, in a suitable grinding mill inwhich the porous particles are reduced in size and dispersed. Thedispersant, an important ingredient in the milling, can be chosen toallow the opacifying colorant particles to be milled in the liquidmedium down to a size small enough for incorporation into the discretepores of the porous particles. The dispersants can be selected to obtainefficient opacifying colorant particle size reduction during milling,provide good colloidal stability of the opacifying colorant particles toprevent agglomeration after milling and impart the desired properties ofthe final foamed aqueous composition containing the opacifying colorantsand the porous particles containing them. Alternatively, the opacifyingcolorant also can be incorporated in the continuous polymeric phase as amaster batch of the opacifying colorant and an appropriate resin.

Foamed Aqueous Compositions

Foamed aqueous compositions can be prepared using the proceduresdescribed below wherein an inert gas (such as air) is mechanicallyincorporated into the foamable aqueous composition as described above,which procedures are designed to provide a foam density of at least 0.1g/cm² and up to and including 0.5 g/cm³, or more likely of at least 0.15g/cm³ and up to and including 0.4 g/cm³. Foam density can be determinedgravimetrically by weighing a known volume of the foamed aqueouscomposition.

The foamed aqueous composition according to this invention generally hasat least 35% solids and up to and including 70% solids, or moreparticularly at least 40% solids and up to and including 60% solids.

The five essential components (a) through (e) of the foamed aqueouscomposition are generally present in the same amounts as essentialcomponents in the foamable aqueous composition (described above) as thefoaming process does not appreciably add to or diminish the amounts ofsuch components.

For example, the (a) porous particles (as described above) can bepresent in the foamed aqueous composition in an amount of at least 0.05weight % and up to and including 15 weight %, or typically of at least0.5 weight % and up to and including 10 weight %, based on the totalweight of the foamed aqueous composition.

One or more (b) binder materials (as described above) can be present inan amount of at least 20 weight %, or at least 25 weight % and up to andincluding 70 weight % or typically of at least 30 weight % and up to andincluding 50 weight %, based on the total weight of the foamed aqueouscomposition. In addition, one or more of the binder materials in thefoamed aqueous composition can be curable.

One or more (c) additives (as described above) can be present in anamount of at least 0.0001 weight % and up to and including 30 weight %or typically of at least 0.001 weight %, or even at least 0.01 weight %,and up to and including 20 weight %, based on the total weight of thefoamed aqueous composition. At least one of the (c) additives is asurfactant as described above, and in particularly useful embodiments,the (c) additives comprise a foaming agent and a foam stabilizing agent.Other useful (c) additives can be present as noted above for thefoamable aqueous compositions, also in the amounts noted above. Forexample, some particularly useful embodiments of the foamed aqueouscomposition, the (c) additives comprise two or more materials selectedfrom surfactant that is a foaming agent, a surfactant that is a foamdispersing agent, a tinting agent, an optical brightener, a flameretardant, an antimicrobial agent, and an inorganic filler (such as aclay).

Water is also present as the predominant solvent (at least 75 weight %of total solvent weight), and all of the solvents that are present in anamount of at least 30 weight % and up to and including 70 weight %, ortypically at least 40 weight % and up to and including 60 weight %,based on the total weight of the foamed aqueous composition.

The (e) opacifying colorants (as described above) are generally presentin any suitable amount to provide the desired appearance, coloration,and opacity in the resulting foamed (and dried) opacifying element, Inmany embodiments, the one or more opacifying colorants can be present inan amount of at least 0.001 weight % or at least 0.001 weight % and upto and including 0.5 weight %, or even in an amount of least 0.003weight % and up to and including 0.2 weight %, especially when theopacifying colorant is a carbon black, all weights based on the totalweight of the foamed aqueous composition.

In some embodiments, the foamed aqueous composition comprises at least0.5 weight % and up to and including 10 weight % of the porous particles(as described above) that have a mode particle size of at least 3 μm andup to and including 30 μm, the amount based on the total weight of thefoamed aqueous composition. In addition, discrete pores in such porousparticles can have an average pore size of at least 100 nm and up to andincluding 7000 nm.

Moreover, the foamed aqueous composition can further comprise at least0.001 weight % of the opacifying colorant (described above) within theporous particles. For example, some opacifying colorant can be a carbonblack and present in an amount of at least 0.003 weight % and up to andincluding 0.2 weight % based on the total weight of the foamed aqueouscomposition.

Such opacifying colorant can be within: (i) the continuous polymericphase of the porous particles; (ii) a volume of the first set (oradditional set) of discrete pores; or (iii) both the volume of the firstset (or additional set) of discrete pores and the continuous polymericphase of the porous particles.

In some embodiments of the foamed aqueous composition, porous particlescan be used that further comprise at least a second set of discretepores (different from a “first” set of discrete pores) and an opacifyingcolorant or a tinting colorant can be present within: the continuouspolymeric phase, the volume of the second set of discrete pores, or inboth the continuous polymeric phase and the volume of the second set ofdiscrete pores. First and second sets (or additional sets) of discretepores can be incorporated into the porous particles using manufacturingtechnology described in several references cited above, including U.S.Pat. No. 8,110,628 (Nair et al.).

Foamed, Opacifying Elements

Foamed, opacifying elements can be prepared using methods and systems asdescribed below according to the present invention. Such articlescomprise a target porous substrate and a single dry foamed compositiondisposed generally on only one supporting side of the target poroussubstrate to form a single dry opacifying layer. As described in moredetail, each target porous substrate has two supporting (planar) sides,that is, a first supporting side and a second opposing supporting side.The target porous substrate can have a target light blocking value(LBV_(S)) that is determined as described above.

Each dry foamed composition is derived from a foamed aqueous compositiondescribed above according to the present invention. In all embodiments,each dry foamed composition comprises at least the following fiveessential components (a) through (e) and amounts, all of which aredescribed in more detail above.

Component (a) porous particles are present in an amount of at least 0.1weight % and up to and including 40 weight % or at least 0.5 weight %and up to and including 10 weight % of porous particles that aredescribed in detail above, the amounts based on the total weight of thedry foamed composition, particularly when the porous particles have amode particle size of at least 2 μm and up to and including 50 μm (or atleast 3 μm and up to and including 30 μm) and the first set of discretepores of the porous particles have an average pore size of at least 100nm and up to and including 7,000 nm.

In addition, the dry foamed composition includes component (b) bindermaterial in an at least partially cured or crosslinkable form, which isat least 10 weight % and up to and including 70 weight %, or at least 20weight % and up to and including 60 weight % of one or more at leastpartially cured binder materials. Such at least partially cured bindermaterials are derived by at least partial curing or crosslinking(described below) of the binder materials described above. The notedamounts are based on the total weight of the dry foamed composition.Each of the one or more binder materials has a T_(g) of 25° C. or less,or 0° C. or less.

One or more (c) additives, at least one is a surfactant, are present inan amount of at least 0.2 weight % and up to and including 50 weight %,or at least 1 weight % and up to and including 45 weight %, suchadditives being selected from the group consisting of foaming agents,foam stabilizing agents, plasticizers, inorganic or organic pigments anddyes (for example, pigment or dye colorants different from theopacifying colorants described below), flame retardants, antimicrobials,fungicides, preservatives, pH buffers, optical brighteners, tintingcolorants, metal particles such as metal platelets or metal flakes,thickeners, and inorganic fillers (such as clays) that are not any ofthe other additive materials or opacifying colorants described herein,all of which additives are described in more detail above. The amountsare based on the total weight of the dry foamed composition. As notedabove, most embodiments include at least one surfactant that is afoaming agent and at least one foam stabilizing agent.

Particularly useful one or more (c) additives comprise two or morematerials selected from a foaming agent, a foam stabilizing agent, atinting colorant, an optical brightener, a flame retardant, anantimicrobial agent, and an inorganic filler (such as a clay).

Thus, the foamed, opacifying element can comprise one or more tintingcolorants as (c) additives in the dry foamed composition in an amount ofat least 0.0001 weight % and up to and including 3 weight %, based onthe total weight of the dry foamed composition. Such tinting colorant(s)can be present in at least the porous particles, and can be elsewherealso.

It is also useful to include one or more optical brighteners as (c)additives in an amount of at least 0.001 weight % and up to andincluding 0.4 weight %, based on the total weight of the dry foamedcomposition.

The dry foamed composition is “substantially” dry in nature, meaningthat it comprises less than 5 weight %, or even less than 2 weight %, ofaqueous medium (including water and any other solvents), based on thetotal weight of the dry foamed composition. This amount may not includeany water that can be present in the discrete pores of the porousparticles. The dry foamed composition in the dry opacifying layergenerally comprises at least 90% solids, or at least 95% solids, or evenat least 98% solids.

The dry foamed composition can also contain at least 0.002 weight %, oreven at least 0.02 weight % and up to and including 2 weight % or up toand including 1 weight %, of one or more (e) opacifying colorants (asdescribed above), which opacifying colorants absorb all wavelengths ofthe predetermined electromagnetic radiation (as defined above). Detailsof such opacifying colorants are described above, and the amounts arebased on the total weight of the dry foamed composition. Such opacifyingcolorants can be present within the (a) porous particles or within the(b) binder material, or within both (a) and (b) components.

In some embodiments, a carbon black is present as the (e) opacifyingcolorant in an amount of at least 0.002 weight % and up to and including1 weight %, based on the total weight of the dry foamed composition.

In many embodiments of the foamed, opacifying element, the opacifyingcolorant (such as a carbon black) can be present within: the continuouspolymeric phase of the porous particles; a volume of the first set (oradditional set) of discrete pores; or both the volume of the first set(or additional set) of discrete pores and the continuous polymeric phaseof the porous particles.

In addition, such single dry opacifying layers exhibit a luminousreflectance (opacity) that is greater than 40%, as measured for the Ytristimulus value. For this purpose, luminous reflectance (brightness)is determined as described above.

Dry target porous substrates useful in the practice of the presentinvention can comprise various porous materials such as woven andnonwoven textile fabrics composed of nylon, polyester, cotton, aramide,rayon, polyolefin, acrylic wool, porous glasses, fiberglass fabrics, orfelt or mixtures thereof, or porous polymeric films [such as porousfilms derived from triacetyl cellulose, polyethylene terephthalate(PET), diacetyl cellulose, acetate butyrate cellulose, acetatepropionate cellulose, polyether sulfone, polyacrylic based resin, forexample, poly(methyl methacrylate), a polyurethane-based resin,polyester, polycarbonate, aromatic polyamide, polyolefins (for example,polyethylene and polypropylene), polymers derived from vinyl chloride(for example, polyvinyl chloride and a vinyl chloride/vinyl acetatecopolymer), polyvinyl alcohol, polysulfone, polyether, polynorbomene,polymethylpentene, polyether ketone, (meth)acrylonitrile], porous paperor other porous cellulosic materials, canvases, porous wood, porousplaster and other porous materials that would be apparent to one skilledin the art. The target porous substrates can vary in dry thickness aslong as they are suitable for the desired foamed, opacifying element. Inmost embodiments, the dry target porous substrate thickness is at least50 μm but this can be varied according to the present invention forvarious economic or aesthetic purposes as described herein.

Particularly useful target porous substrates comprise a porous textileweb (such as a flexible porous textile web), a porous polymer film (suchas a woven polyester fabric), a porous cellulosic material (such asporous papers), a porous ceramic material, or a porous glass material.

The target porous substrates can be surface treated by various processesincluding corona discharge, glow discharge, UV or ozone exposure, flame,or solvent washing in order to promote desired physical properties.

The light blocking value of the target porous substrate (LBV_(S)) can bedetermined as described above.

Generally, the foamed opacifying elements prepared by the presentinvention are designed with a single dry opacifying layer disposed onone supporting (planar) side of the target porous substrate as describedabove using techniques described below, and the single dry opacifyinglayer is the only (outermost) layer disposed on the target poroussubstrate.

Attractive finishes can be imparted to the foamed, opacifying element byfor example, flocking the foamed aqueous composition that is disposed onthe target porous substrate. Flock or very short (0.2 mm and up toseveral mm) fibers can be disposed in the single dry opacifying layerusing either by electrostatic or mechanical techniques on the outermostsurface of the foamed aqueous composition before or during drying.

The backside of the foamed, opacifying element can be modified withembossing or printing as noted above to modify the second opposingsupporting side of the target porous substrate, using known procedures.

Method of Making Foamed, Opacifying Elements

The present invention can be used to provide a foamed, opacifyingelement having a target (or desired or predetermined) light blockingvalue (LBV_(T)), which foamed, opacifying element is expected tocomprise or include a specific predetermined or chosen target poroussubstrate having a first supporting side and an opposing secondsupporting side. In many instances, a customer may determine or choosethe target porous substrate as well as the LBV_(T), and then the presentinvention can be used to advantage to design and manufacture the desiredfoamed, opacifying element with such specifications in a most efficientmanner. Thus, a customer or manufacturer can choose suitablespecifications and thereby provide options for custom-design of foamed,opacifying elements having various specifications and then sell suchmaterials to commercial and retail businesses.

Each target porous substrate has an inherent light blocking value(LBV_(S)) due to its type of weave, the tightness of its weave, itscolor, its pattern, its dry thickness, and porosity in general. In mostinstances, this LBV_(S) is unknown for each target porous substrate.Thus, prior to, simultaneously with, or subsequently to choosing theLBV_(T), the LBV_(S) can be determined for example, using the proceduredescribed above.

Once a target porous substrate and its LBV_(S) are known, one cancalculate LBV_(T-S) that is the difference between LBV_(T) and LBV_(S),which value then tells the user of the present invention how a flammableaqueous composition can be chosen to provide a single dry opacifyinglayer that will essentially match LBV_(T-S).

Such foamable aqueous composition can be chosen using trial and errorbased on past experience, but it can also be chosen based on certaintypes of properties it may have, for example, coloration, opacity,reflectance, and chemical properties such as fire retardation anddesired antimicrobial effects.

It is also important to note, that once a foamable aqueous compositionis chosen, it can be important for achieving a desired LBV_(T) with agiven target porous substrate to determine an optimal foam density forthe corresponding foamed aqueous composition. This optimal foam densitycan be readily determined by routine experimentation in the foamingprocedure (described below) whereby the foaming conditions are varieduntil the desired foam density is identified.

Once a foamable aqueous composition is chosen, one can use amathematical formula to determine a dry coating weight of the chosenfoamable aqueous composition that will provide the desired LBV_(T-S) forthe single dry opacifying layer. This mathematical formula can beobtained from a look-up table (LUT) that is created by first coating,drying, and crushing several dry coating weights of the chosen foamableaqueous composition (after foaming) on a porous substrate with a knownlight blocking value. The actual dry coating weight and resulting lightblocking value of each foamed, opacifying element (LBV_(T)) is thenmeasured. The dry coating weights are then plotted versus LBV_(T-S) andthe best fit equation is determined using regression analysis. TheLBV_(T-S) is dependent upon various factors relating to the specificcomposition of the foamable aqueous composition that is chosen as wellas the intended dry coating weight of the resulting single dryopacifying layer. Further, the outcome of the regression analysisprovides a prediction of desired dry coating weights from the LBV_(T-S)values. The LUT thus created for the prediction of dry coating weightfrom the LBV_(T-S) had an average prediction error of less than 7%.

As used herein, unless otherwise indicated, the terms “dry coatingweight” and “coating weight” are meant to be interchangeable. Thus, thedry coating weight (or coating weight) in reference to the dryopacifying layer is defined in terms of g/m² and intended to refer onlyto the dry applied weight (or % solids) of the single dry opacifyinglayer. The dry coating weight can for example range from at least 20g/m² and up to and including 400 g/m², but the present invention is notto be limited to this range since a skilled worker may have a desire tomanufacture a foamed, opacifying element with a single dry opacifyinglayer having either lower or higher dry coating weight for a givenpurpose.

In some instances, a user of the present invention will have access to aset of multiple (two or more) foamable aqueous compositions (each ofwhich can be converted by foaming into multiple corresponding foamedaqueous compositions). A unique mathematical formula can be determinedfor each foamable aqueous composition in the set. Thus, a set ofmathematical formulae (for example, in the form of a LUT) associatedwith the set of foamable aqueous compositions can be determined and usedas needed. The LUT then relates coating weights of the respectivefoamable aqueous compositions to respective light blocking values forthe respective resulting dry opacifying layers.

Once the necessary dry coating weight is identified for the targetporous substrate and the chosen LBV_(T) and foamable aqueouscomposition, the chosen foamable aqueous composition is applied (afterfoaming), at that dry coating weight, using suitable coating equipmentand means described below, to form a single dry opacifying layer as theonly layer disposed on the first supporting side of the target poroussubstrate, such that the resulting single dry opacifying layer has alight blocking value that is equal to LBV_(T-S), ±10%, or moreparticularly, equal to LBV_(T-S), ±7%.

Specifically, once a necessary dry coating weight is determined, achosen foamable aqueous composition as described above comprising thefive essential components (a) through (e) in the described amounts canbe used to provide a single dry opacifying layer in the followingmanner.

The chosen foamable aqueous composition is aerated to provide acorresponding chosen foamed aqueous composition having a foam density ofat least 0.1 g/cm³ and up to and including 0.5 g/cm³, or of at least0.15 g/cm³ and up to and including 0.4 g/cm³. This aeration procedurecan be carried out using any suitable conditions and equipment thatwould be readily apparent to one skilled in the art in order to create a“foam” in the presence of a foaming agent as the (c) additive surfactantdescribed above. For example, aeration can be carried out bymechanically introducing air or an inert gas (such as nitrogen or argon)in a controlled manner. High shear mechanical aeration can be carriedout using sonication or high speed mixers, such as those equipped with acowles blade, or with commercially available rotorstator mixers withinterdigitated pins such as an Oakes mixer or a Hobart mixer, byintroducing air under pressure or by drawing atmospheric air into thefoamable aqueous composition by the whipping action of the mixer.Suitable foaming equipment can be used in a manner to provide thedesired foam density with modest experimentation. It can be useful tochill or cool the chosen foamable aqueous composition below ambienttemperature to increase its stability by increasing its viscosity, andto prevent its collapse. This chilling operation can be carried outimmediately before, after, or during the aeration procedure. Stabilityof the corresponding chosen foamed aqueous composition can also beenhanced by the presence of a foam stabilizing agent as another of the(c) additives.

Once the corresponding chosen foamed aqueous composition has beenformed, it can be disposed onto one supporting side (or planar surface)of a target porous substrate (described above). This procedure can becarried out in any suitable manner that does not undesirably diminishthe foam density (or foam structure) of the corresponding chosen foamedaqueous composition. For example, a planar surface of the target poroussubstrate can be coated with the corresponding chosen foamed aqueouscomposition using any suitable known coating equipment (floating knife,hopper, blade, or gap) and coating procedures including but not limitedto blade coating, gap coating, slot die coating, X-slide hopper coating,or “knife-over-roll” operation. For example, useful layer forming(coating) means are described in U.S. Pat. No. 4,677,016 (Ferziger etal.), the disclosure of which is incorporated herein by reference.

Thus, the corresponding chosen foamed aqueous composition can bedisposed directly onto an outer surface of the target porous substrate(“directly” means no intervening or intermediate layers) such as aporous woven cloth fabric, a porous fiberglass fabric, or a porouscellulosic material.

Once the corresponding chosen foamed aqueous composition has beendisposed on a planar surface of the target porous substrate, it isgenerally dried to become “substantially” dry (to be defined in relationto the amount of water that is present), and at least partially cured(meaning the one or more binder materials are at least partially curedor crosslinked), simultaneously or in any order, to provide a dry foamedcomposition (and single dry opacifying layer) on a first supporting sideof the target porous substrate. Drying and at least partial curing canbe accomplished by any suitable means such as by heating with warm orhot air, microwaves, or IR irradiation at a temperature and timesufficient for at least drying and at least partial curing (for example,at less than 180° C.). Curing the binder materials can be promoted byheat or radiation or other conditions to which the binder materials areresponsive for crosslinking. In some embodiments, a suitablefunctionalized latex composition is used as the binder material. Uponheating, the binder material(s) dries, and a possible curing orcrosslinking reaction takes place between reactive side groups ofsuitable curable polymer chains. If the particular binder material isnot itself heat reactive, suitable catalysts or curing (crosslinking)agents can be added to the chosen foamable aqueous composition topromote curing or crosslinking.

After drying and at least partially curing, the dry foamed compositionon the target porous substrate is then crushed or densified on thetarget porous substrate to form a densified single dry opacifying layerin the foamed, opacifying element. This process can be carried out inany suitable manner but it is generally carried out by a process thatprovides pressure to the dry foamed composition on the target poroussubstrate, for example, by passing the target porous substrate with thedry foamed composition through a compression calendering operation,pressing operation, or embossing operation, or a combination thereof.For example, the target porous substrate and dry foamed composition canbe passed through a combination of calendering and embossing rollers toreduce the thickness of and density the foam in the dry foamedcomposition. The thickness of the dry foamed composition can be reducedby at least 20% during such an operation. This process of crushing thedry foamed composition can be considered a “densifying operation” as thedry foamed composition is made denser when it is pressed together,usually into a thinner layer. The thickness of the dry foamedcomposition before and after crushing (densifying) can be determined bya known technique such as laser profilometry.

It is also possible to provide an embossed design on the outermostsurface of the single dry opacifying layer of the foamed, opacifyingelement during the densifying operation such as for example, bypatterned embossing or calendering, to create selected regions of highor low opacity and thickness. The resulting embossed design can beviewed from either side in transmission.

It is further possible to print images on the outer surface of thesingle dry opacifying layer of the foamed, opacifying element or on thebackside (second supporting side) of the target porous substrate, or onboth, using any suitable printing means such as inkjet printing orflexographic printing, thereby forming printed images of text, pictures,symbols, other objects, or combinations thereof. Such printed images canbe visible, or they can invisible to the unaided eye (for example, usingfluorescent dyes in the printed images). Alternatively, the single dryopacifying layer can be covered by printing or other means, with acolorless layer to provide a glossy finish.

The crushing or densifying process described above can be carried out atany suitable temperature including room temperature (for example, 20°C.) and up to and including 90° C., or more likely at a temperature ofat least 20° C. and up to and including 80° C.

After densifying the dry foamed composition in the single dry opacifyinglayer, it can be subjected to conditions that promote further curingsuch as those conditions that are described above for the initialdrying/curing operations.

System

The present invention provides a system of features for carrying out thepresent invention in order to obtain a desired foamed, opacifyingelement having a target light blocking value (LBV_(T)).

This system comprises three essential features: (A) a set of foamableaqueous compositions; (B) a set of mathematical formulae associated withthe set of foamable aqueous compositions of (A); and (C) a dataprocessor for carrying out a method for generating the foamed,opacifying element with LBV_(T) using (A) and (B).

(A) Foamable Aqueous Compositions:

A “set” of foamable aqueous compositions refers to a multiplicity or twoor more of individual foamable aqueous compositions prepared with atleast the five essential components (a) through (e) described above.Each foamable aqueous composition has at least 35% solids and up to andincluding 70% solids, independently of the other foamable aqueouscompositions in the set. Thus, the multiple foamable aqueouscompositions can have the same or different % solids.

In addition, while each of the multiple foamable aqueous compositionscomprises each of the essential five (a) through (e) components, theamounts of each component can be the same or different, and in mostinstances, there is at least one feature that is different (either inkind or amount, or both) so that the set of foamable aqueouscompositions are capable of providing a range of features (opacity, drythickness, color, and other properties described above) in resulting dryopacifying layers. The kind or amount of optional components can alsovary among the individual foamable aqueous compositions.

Moreover, the foam density of the individual foamed aqueous compositionscan be the same or different within the set of foamable aqueouscompositions. Since the foam density can influence coating weight, lightblocking values, and other optical, physical, or chemical properties,foam density can be another parameter that is adjusted by themanufacturer of a foamed, opacifying element so as to meet a customer'sdesired specifications. For example, a higher foam density in the rangedescribed above can provide a thinner dry opacifying layer but yet ahigher dry coating weight, whereas a lower foam density within thatrange can provide a thicker dry opacifying layer, but yet a lower drycoating weight, for the same LBV_(T-S).

It would be understood that the set of foamable aqueous compositions canbe used, upon foaming, to provide a set of corresponding foamed aqueouscompositions.

(B) Set of Mathematical Formulae:

Each of the foamable aqueous compositions in the set described above hasa mathematical formula associated therewith, that is determined asdescribed above in the “Method of Making Foamed, Opacifying Element”section. Each mathematical formula relates dry coating weight of therespective foamable aqueous composition to a respective light blockingvalue of that foamable aqueous composition when it has been foamed,applied to a target porous substrate, dried, and crushed, all of whichprocedures are described above.

In order to obtain each mathematical formula, first a correspondingchosen foamed aqueous composition is applied at different dry coatingweights to a porous substrate having a determined light blocking value(LBV_(S)). The actual dry coating weight and light blocking value ofeach foamed, opacifying element (LBV_(T)) is then determined, and theLBV_(T-S) values are calculated. Each dry coating weight is then plottedversus LBV_(T-S) and the best fit equation is determined usingregression analysis.

(C) Data Processor:

The method of the present invention can be carried out to provide afoamed, opacifying element having the target light blocking value(LBV_(T)) using a suitable data processor. This can be as simple as aLUT in which several dry coating weights are listed along with thecorresponding light blocking values of the corresponding chosen foamedaqueous composition at that dry coating weight. The processor can alsotake the form of a computer program or spreadsheet in which the desiredlight blocking value and the target porous substrate serve as input andthe chosen dry coating weight of the corresponding chosen foamed aqueouscomposition is provided as output.

In some embodiments, the target porous substrate is chosen and themathematical formula for each of the foamable aqueous compositions inthe set is determined by considering or using various economic aspectsor aesthetic aspects in the design of the method for making a desiredfoamed, opacifying element.

By “economic aspects,” we mean for example, that instead of the samecoating weight being applied to all target porous substrates, only theminimum amount of foamed aqueous composition needs to be applied whenthe LBV_(S) is taken into account, thereby minimizing dry coating weightand waste of excess foamed aqueous composition.

By “aesthetic aspects,” we mean for example, that inexpensive,lightweight fabrics can be made to feel and look more luxurious byapplying a greater dry coating weight of the foamed aqueous compositiononto those particular fabrics.

The present invention provides at least the following embodiments andcombinations thereof, but other combinations of features are consideredto be within the present invention as a skilled artisan would appreciatefrom the teaching of this disclosure:

1. A system for providing a foamed, opacifying element having a targetlight blocking value (LBV_(T)), comprising:

(A) a set of foamable aqueous compositions, each of the foamable aqueouscompositions independently having at least 35% solids and up to andincluding 70% solids, and independently comprising:

-   -   (a) at least 0.05 weight % and up to and including 15 weight %        of porous particles, each porous particle comprising a        continuous polymeric phase and a first set of discrete pores        dispersed within the continuous polymeric phase, the porous        particles having a mode particle size of at least 2 μm and up to        and including 50 μm and a porosity of at least 20 volume % and        up to and including 70 volume %, and the continuous polymeric        phase having a glass transition temperature greater than 80° C.        and comprising a polymer having a viscosity of at least 80        centipoises and up to and including 500 centipoises at a shear        rate of 100 sec′ in ethyl acetate at a concentration of 20        weight % at 25° C.,    -   (b) at least 20 weight % of a binder material;    -   (c) at least 0.0001 weight % of one or more additives comprising        at least one surfactant;    -   (d) water; and    -   (e) at least 0.001 weight % of an opacifying colorant different        from all of the one or more (c) additives, which opacifying        colorant absorbs predetermined electromagnetic radiation,    -   all amounts being based on the total weight of the foamable        aqueous composition, and wherein each of the foamable aqueous        compositions can be foamed to provide a foamed aqueous        composition having a foam density of at least 0.1 g/cm³ and up        to and including 0.5 g/cm³;

(B) a set of mathematical formulae associated with the set of foamableaqueous compositions, wherein the set of mathematical formulae relatecoating weight of the respective foamable aqueous compositions torespective light blocking values; and

(C) a data processor configured to perform a method for generating thefoamed, opacifying element having the target light blocking value(LBV_(T)), the method comprising:

-   -   choosing a target porous substrate having a first supporting        side;    -   choosing a target light blocking value (LVB_(T));    -   determining a light blocking value (LBV_(S)) of the target        porous substrate;    -   calculating LBV_(T-S) as a difference between LBV_(T) and        LBV_(S);    -   choosing a foamable aqueous composition;    -   using a mathematical formula to obtain a dry coating weight for        a single dry opacifying layer derived from the chosen foamable        aqueous composition; and    -   using the dry coating weight to form the single dry opacifying        layer as the only layer disposed on the first supporting side of        the target porous substrate, such that the single dry opacifying        layer has a light blocking value that is equal to LBV_(T-S),        +10%.

2. A method for providing a foamed, opacifying element having a targetlight blocking value (LBV_(T)) and comprising a target porous substratehaving a first supporting side and an opposing second supporting side,the method comprising:

choosing a target porous substrate;

choosing a target light blocking value (LBV_(T));

determining a light blocking value (LBV_(S)) of the target poroussubstrate;

calculating LBV_(T-S) as a difference between LBV_(T) and LBV_(S);

choosing a foamable aqueous composition;

using a mathematical formula to obtain a dry coating weight for a singledry opacifying layer derived from the chosen foamable aqueouscomposition; and

using the dry coating weight to form the single dry opacifying layer asthe only layer disposed on the first supporting side of the targetporous substrate, such that the single dry opacifying layer has lightblocking value that is equal to LBV_(T-S), +10%,

wherein the chosen foamable aqueous composition has at least 35% solidsand up to and including 70% solids, and comprises:

(a) at least 0.05 weight % and up to and including 15 weight % of porousparticles, each porous particle comprising a continuous polymeric phaseand a first set of discrete pores dispersed within the continuouspolymeric phase, the porous particles having a mode particle size of atleast 2 μm and up to and including 50 μm and a porosity of at least 20volume % and up to and including 70 volume %, and the continuouspolymeric phase having a glass transition temperature greater than 80°C. and comprising a polymer having a viscosity of at least 80centipoises and up to and including 500 centipoises at a shear rate of100 sec⁻¹ in ethyl acetate at a concentration of 20 weight % at 25° C.,

(b) at least 20 weight % of a binder material;

(c) at least 0.0001 weight % of one or more additives comprising atleast one surfactant;

(d) water; and

(e) at least 0.001 weight % of an opacifying colorant different from allof the one or more (c) additives, which opacifying colorant absorbspredetermined electromagnetic radiation,

all amounts being based on the total weight of the chosen foamableaqueous composition, and wherein the chosen foamed aqueous compositioncan be foamed to provide a foamed aqueous composition having a foamdensity of at least 0.1 g/cm³ and up to and including 0.5 g/cm³.

3. Embodiment 1 or 2, wherein the foamed, opacifying element has aluminous reflectance that is greater than 40% as measured by the Ytristimulus value.

4. Any of embodiments 1 to 3, wherein the target porous substratecomprises a porous textile web, porous polymer film, porous cellulosicmaterial, porous ceramic material, or porous glass material.

5. Any of embodiments 1 to 4, wherein the chosen foamable aqueouscomposition comprises a tinting colorant, a flame retardant, anantimicrobial agent, or a flocking agent as a (c) additive.

6. Any of embodiments 1 to 5, wherein the continuous polymeric phasecomprises one or more cellulose polymers.

7. Any of embodiments 1 to 6, wherein the continuous polymeric phasecomprises at least 70 weight %, based on the total polymer weight in thecontinuous polymeric phase, of one or more polymers derived from one ormore of cellulose acetate, cellulose butyrate, cellulose acetatebutyrate, and cellulose acetate propionate.

8. Any of embodiments 1 to 7, wherein the opacifying colorant is acarbon black that is present in an amount of at least 0.003 weight % andup to and including 0.2 weight %, based on the total weight of thechosen foamable aqueous composition.

9. Any of embodiments 1 to 8, wherein the chosen foamable aqueouscomposition comprises at least 0.5 weight % and up to and including 10weight % of the porous particles, based on the total weight of thechosen foamable aqueous composition, which porous particles have a modeparticle size of at least 3 μm and up to and including 30 μm.

10. Any of embodiments 1 to 9, wherein the one or more (c) additivesfurther comprise metal flakes that are present within the porousparticles.

11. Any of embodiments 1 to 10, wherein the surfactant of the one ormore (c) additives is a foaming agent and the one or more (c) additivesfurther comprise a foam stabilizing agent.

12. Any of embodiments 1 to 11, wherein the one or more (c) additivesfurther comprise an optical brightener in an amount of at least 0.01weight % and up to and including 2 weight %, based on the total weightof the chosen foamable aqueous composition.

13. Any of embodiments 1 to 12, wherein the one or more (c) additivescomprise two or more materials selected from a foaming agent, a foamdispersing agent, a tinting colorant, an optical brightener, a flameretardant, an antimicrobial agent, and an inorganic filler.

14. Any of embodiments 1 to 13, wherein the one or more (c) additivescomprise an antimicrobial agent comprising silver metal, asilver-containing compound, copper metal, a copper-containing compound,or a mixture of any of these.

15. Any of embodiments 1 to 14, wherein choosing the target poroussubstrate and determining the mathematical formula for each of thefoamable aqueous compositions are carried out using economic aspects oraesthetics aspects.

The following Examples are provided to illustrate the practice of thisinvention and are not meant to be limiting in any manner. The followingmaterials were used in the various coating formulations and foamed,opacifying elements.

Materials used to make representative Foamable Aqueous Compositions thatcan be used in the practice of the present invention:

The continuous polymeric phase polymers were the Eastman™ CelluloseAcetate Butyrate 381-0.5 (CAB), a cellulose ester, T_(g) of 130° C.(obtained from Chem Point); and Kao KBT-382, T_(g) of 60° C., abis-phenol type polyester [obtained from Kao Specialties Americas LLC, apart of Kao Corporation (Japan)].

NALCO® 1060 containing colloidal silica was obtained from Nalco ChemicalCompany as a 50 weight % aqueous dispersion.

The poly(methylamino ethanol adipate) (AMAE) co-stabilizer was preparedusing known procedures and starting materials.

Carboxy methylcellulose (CMC, 250,000 kDa) was obtained from AcrosOrganics or from Ashland Aqualon as Aqualon 9M31F. These products wereused interchangeably.

The amphiphilic block copolymer of polyethylene oxide andpolycaprolactone (PEO-b-PCL) 5K-20K, was prepared using the proceduredescribed in U.S. Pat. No. 5,429,826 (Nair et al.) where the firstnumber is the molecular weight of the hydrophilic block segment, PEO,and the second number is the molecular weight of the oleophilic blocksegment, PCL.

TERGITOL® 15-S-7, a C12-C14 secondary alcohol surfactant having an HLBvalue of 12.4, was obtained from the Dow Chemical Corp. The opticalbrightener TINOPAL® OB CO was obtained from BASF Corporation.

The porous substrates used in the Examples below were various porouswoven fabrics, porous polyester materials, and porous cotton materials,all having a weight of approximately 80-110 g/m².

The carbon black (K) opacifying colorant used as an aqueous dispersionwas Regal 330 (Cabot Corp.) that was hydrophobically surface modified.

The yellow (Y1) tinting colorant, Pigment Yellow 83 (Monolite DiarylideYellow HR) was obtained from Heubach, Heucotech Ltd.

The yellow (Y2) tinting colorant, Pigment Yellow 3 (Hansa Yellow 3) wasobtained from Lansco Colors.

The cyan (C) tinting colorant, Pigment Blue 15:3 (Sunfast Blue 15:3) wasobtained from Sun Chemical.

The magenta (M) pigment, Pigment Red 185 (Graphtol Carmine HF4C) wasobtained from Clariant.

DISPERBYK® 190, a copolymer derived from polystyrene, polypropyleneglycol, and polyethylene glycol, was obtained from BYK-Chemie USA.

SOLSPERSE® 43000, a polyacrylate polymeric dispersant, was obtained fromLubrizol Corp.

EAGLETEX® C-3018 and EAGLEBAN® FRC-0307 Drapery Compounds were obtainedfrom Eagle Performance Products, where the binder material was aself-crosslinking terpolymer derived from acrylonitrile, n-butylacrylate, and ethyl acrylate and having a glass transition temperatureof −10° C.

Measurements:

The mode particle size of the porous particles was measured using aSysmex FPIA-3000 automated particle size analyzer from MalvernInstruments. The particle size of the dispersed pigments was determinedusing light scattering.

The porosity of the porous particles was measured using the knownmercury intrusion porosimetry method.

Preparation of Pigment Dispersions for Porous Particles:

All pigment (opacifying colorants and tinting colorants) dispersionswere prepared by combining dry pigment, a dispersant, and a liquid in asuitable milling vessel. The particle size of each pigment was reducedby milling it using ceramic media until all pigment particles werereduced below a diameter of 1 μm as determined by optical microscopy.The dispersions were further diluted in the same liquid medium forincorporation into porous particles or foamed aqueous composition. Thedispersions varied in the type of pigment, dispersant and dispersantlevel relative to pigments shown below in TABLE I. Dv is the volumeweighted mean diameter, in nanometers. In TABLE I, the Dispersion isidentified by the pigments (K, Y1, Y2, C, or M).

TABLE I Dispersions Dispersant (weight % of Pigment Dv DispersionPigment Pigment) Weight % (nm) D-K K SOLSPERSE ® 10.72 101 43000 (25)D-Y1 Y1 SOLSPERSE ® 8.60 247 43000 (20) D-Y2 Y2 SOLSPERSE ® 16.83 28943000 (20) D-C C SOLSPERSE ® 19.08 139 43000 (30) D-M M Disperbyk ®15.12 289  190 (20)

Preparation of Porous Particles:

The various porous particles used for preparing a foamed, opacifyingelement are described below and TABLE II below summarizes thecharacteristics of the particles. All of the porous particles contained1 weight % of optical brightener in the continuous polymeric phase.

P1 Porous Particles Containing 1 Weight % Opacifying Colorant (K) in theDiscrete Pores and Kao KBT382 in Continuous Polymeric Phase

An aqueous phase was made up by dissolving 68.2 g of CMC in 3,450 gramsof distilled water and adding to 134 g of the D-K dispersion containing18.6 weight % of the surface modified carbon black. This aqueous phasewas dispersed in 11363 grams of an oil phase containing 2475 grams ofKao KBT382 polyester and 25 grams of the optical brightener, TINOPAL® OBCO in ethyl acetate using a homogenizer. The resulting water-in-oilemulsion was dispersed using the Silverson L4R homogenizer for twominutes at 1200 RPM, in 54,338 grams of a 200 mmolar pH 4 acetate buffercontaining 3,050 grams of NALCO® 1060 colloidal silica, followed byhomogenization in an orifice homogenizer at 1000 psi (70.4 kg/cm²) toform a water-in-oil-in-water double emulsion. The ethyl acetate wasremoved under reduced pressure at 40° C. after dilution of thewater-in-oil-in-water emulsion with an equal weight of water. Theresulting suspension of solidified porous particles was filtered and theP1 porous particles were washed with water several times, followed byrinsing with a 0.1 weight % solution of TERGITOL® 15-S-7 surfactant. Theisolated P1 porous particles were then air dried. Typically, thediscrete pores contained within the porous particles prepared accordingto this procedure had an average diameter of from 150 nm and up to andincluding 1,500 nm.

P2 Porous Particles Containing 1 Weight % Yellow Pigment (Y1) in theDiscrete Pores and 1 Weight % Optical Brightener in Continuous PolymericPhase Cellulose Acetate Butyrate to Provide Tinting Colorant

An aqueous phase was made up by dissolving 5 grams of CMC in 240.5 gramsof distilled water and adding to 11.6 grams of the D-Y1 dispersioncontaining 8.6 weight % of PY83. This aqueous phase was dispersed in831.8 grams of an oil phase containing 97.7 grams of CAB, 2 grams ofPEO-PCL and 1 gram of the optical brightener, TINOPAL OB CO in ethylacetate using a homogenizer. A 975-gram aliquot of the resultingwater-in-oil emulsion was dispersed using the Silverson L4R homogenizerfor two minutes at 1200 RPM, in 1625 grams of a 200 mmolar pH 4 acetatebuffer containing 39 grams of NALCO® 1060 colloidal silica, and 9.75grams of AMAE co-stabilizer followed by homogenization in an orificehomogenizer at 1000 psi (70.4 kg_(f)/cm²) to form awater-in-oil-in-water double emulsion. The ethyl acetate was removed,and the resulting P2 porous particles were washed and isolated asdescribed for P1

P3 Porous Particles Containing 1 Weight % Opacifying Colorant (K) in theDiscrete Pores and 1 Weight % Optical Brightener in Continuous PolymericPhase Cellulose Acetate Butyrate

The P3 porous particles were prepared as described for the P2 porousparticles except that the D-K dispersion was used in place of the D-Y1dispersion.

P4 Porous Particles Containing 5 Weight % Yellow Pigment (Y2) in theDiscrete Pores and 1 Weight % Optical Brightener in Continuous PolymericPhase Cellulose Acetate Butyrate

The P4 porous particles were prepared as described for the P2 porousparticles except that the D-Y2 dispersion was used in place of the D-Y1dispersion.

P5 Porous Particles Containing 5 Weight % Cyan Pigment (C) in theDiscrete Pores and 1 Weight % Optical Brightener in Continuous PolymericPhase Cellulose Acetate Butyrate

The P5 porous particles were prepared as described for the P2 porousparticles except that the D-C dispersion was used in place of the D-Y1dispersion.

P6 Porous Particles Containing 5 Weight % Magenta Pigment (M) in theDiscrete Pores and 1 Weight % Optical Brightener in Continuous PolymericPhase Cellulose Acetate Butyrate

The P6 porous particles were prepared as described for the P2 porousparticles except that the D-M dispersion was used in place of the D-Y1dispersion.

P7 Porous Particles Containing 0.8 Weight % Opacifying Colorant (K) inthe Discrete Pores and 1 Weight % Optical Brightener in ContinuousPolymeric Phase Cellulose Acetate Butyrate

The P7 porous particles were prepared as described for the P3 porousparticles except that the amount of the D-K dispersion used was lower toobtain the desired level of K in the porous particles.

P8 Porous. Particles Containing No Opacifying Colorant and 1 Weight %Optical Brightener in Continuous Polymeric Phase Cellulose AcetateButyrate

The P8 porous particles were prepared as described for the P2 porousparticles except that no pigment dispersion was used in the preparation.

TABLE II Porous Particle size Porosity Particles Features (μm) (Vol %)P1 1 weight % K in discrete pores and 4.5 28 continuous polymeric phaseKao KBT382 P2 1 weight % Yellow Pigment (Y1) 5.9 56 in the discretepores and continuous polymeric phase CAB to provide tinting colorant P31 weight % K in discrete pores and 6.8 57 continuous polymeric phase CABP4 5 weight % Yellow Pigment (Y2) 5.7 52 in the discrete pores andcontinuous polymeric phase CAB to provide tinting colorant P5 1 weight %Cyan Pigment (C) in 6.8 52 the discrete pores and continuous polymericphase CAB to provide tinting colorant P6 1 weight % Magenta Pigment (M)5.7 57 in the discrete pores and continuous polymeric phase CAB toprovide tinting colorant P7 0.8 weight % K in discrete pores 6.6 49 andcontinuous polymeric phase CAB P8 no opacifying colorant and in 7.6 54continuous polymeric phase CAB

Preparation of Foamable Aqueous Compositions; Foamed AqueousCompositions; and Foamed, Opacifying Elements:

Representative foamable aqueous compositions that can be included in a“set” of foamable aqueous compositions are described as follows.

In general, each foamable aqueous composition was made by incorporatingthe appropriate porous particles in either a 48 weight % solidsEAGLETEX® C-3018 Drapery Compound or a 55 weight % solids EAGLEBAN®FRC-0307 Drapery Compound. For each foamed aqueous composition, thedrapery compound was added to an appropriately sized container. Porousparticles in the various examples were dispersed into the mixture bystirring at 1200 rev/minute with a 50 mm diameter Cowles blade atambient temperature for 30-60 minutes. Each of the resulting dispersions(foamable aqueous composition) was used to prepare a foamed aqueouscomposition under pressure using an Oakes 2M Laboratory Mixer Model2MBT1A. Each resulting foamed aqueous composition, having a density offrom 0.20 g/cm³ to 0.25 g/cm³, was coated onto a surface of the poroussubstrate described above with a coating knife, dried at a temperatureof from 120° C. to 160° C. as described below until the moisture contentwas less than 2 weight %, and crushed (“densified”) on the poroussubstrate between hard rollers under pressure.

Foamed, Opacifying Element 1:

A foamable aqueous composition was prepared from 940.3 grams ofEAGLETEX® C-3018 Drapery Compound and 59.7 grams of a 49.76 weight %aqueous dispersion of the P3 porous particles. This foamable aqueouscomposition was foamed (aerated) to provide a foamed aqueous compositionthat was coated onto a surface of the porous substrate with a coatingknife with a 2.794 mm (0.110 inch) gap. The coating was dried at 120° C.for 10 minutes in a forced air oven. The dry foamed composition (dryopacifying layer) contained 6.10 weight % of the P3 porous particles,0.0610 weight % of carbon black, and 0.136 g/m² of carbon black on a dryweight basis. The resulting foamed, opacifying element exhibited anLBV-r of 5 for the dry opacifying layer dry coating weight of 223 g/m²and a luminous reflectance value of 53.

Foamed, Opacifying Element 2:

A foamable aqueous composition was prepared with 1,399.8 grams ofEAGLETEX® C-3018 Drapery Compound and 100.2 grams of a 49.25 weight %aqueous dispersion of the P7 porous particles. This foamable aqueouscomposition was foamed (aerated) and the resulting foamed aqueouscomposition was coated onto a surface of the porous substrate describedabove with a coating knife with a 2.54 mm (0.100 inch) gap. The dryfoamed composition (dry opacifying layer) in the foamed, opacifyingelement contained 6.71 weight % of the P7 porous particles, 0.0557weight % of carbon black, and 0.136 g/m² of carbon black on a dry weightbasis. This inventive foamed, opacifying element exhibited an LBV of 5.8for the dry opacifying layer dry coating weight of 244 g/m², and it hada luminous reflectance value of 52.

Foamed, Opacifying Element 3:

A foamable aqueous composition was prepared with 1,388.3 grams ofEAGLETEX® C-3018 Drapery Compound, 100.2 grams of a 49.25 weight %aqueous dispersion of the P7 porous particles, and 11.5 grams of a 49.22weight % aqueous dispersion of the P2 porous particles. This aqueousfoamable composition was foamed (aerated) and the resulting foamedaqueous composition was coated onto a surface of the porous substratedescribed above with a coating knife with a 2.54 mm (0.100 inch) gap.The dry foamed composition (dry opacifying layer) in this foamed,opacifying element contained 7.49 weight % of the P7 and P2 porousparticles, 0.0557 weight % of carbon black, 0.0078 weight % of yellowpigment Y1, and 0.137 g/m² of carbon black on a dry weight basis. Thisinventive foamed, opacifying element exhibited an LBV of 5.9 for a dryopacifying layer dry coating weight of 246 g/m², and a luminousreflectance value of 52 and exhibited a yellow tinted appearance thatwas reflected in the b* value of 0.46.

Foamed, Opacifying Element 4:

A foamable aqueous composition was prepared with 1,388.9 grams ofEAGLETEX® C-3018 Drapery Compound, 100.2 grams of a 49.25 weight %aqueous dispersion of the P7 porous particles, and 10.9 grams of a 52.39weight % aqueous dispersion of the P5 porous particles. This compositionwas foamed (aerated) and the resulting foamed aqueous composition wascoated onto a surface of the porous substrate described above with acoating knife with a 2.54 mm (0.100 inch) gap. The dry foamedcomposition (dry opacifying layer) in the resulting foamed, opacifyingelement contained 7.48 weight % of the P7 and P5 porous particles,0.0557 weight % of carbon black, 0.0078 weight % of cyan pigment C, and0.135 g/m² of carbon black on a dry weight basis. This foamed,opacifying element exhibited an LBV of 6 for the dry opacifying layerdry coating weight of 242 g/m², and a luminous reflectance value of51.5, and also exhibited a cyan tinted appearance that was reflected inthe b* value of −1.82.

Foamed, Opacifying Element 5:

A foamable aqueous composition was prepared with 926.0 grams ofEAGLETEX® C-3018 Drapery Compound, 66.8 grams of a 49.25 weight %aqueous dispersion of the P7 porous particles, and 7.2 grams of a 53.46weight % aqueous dispersion of the P6 porous particles. This compositionwas foamed (aerated) and the resulting foamed aqueous composition wascoated onto a surface of the porous substrate described above with acoating knife with a 2.54 mm (0.100 inch) gap. The dry foamedcomposition of the resulting foamed, opacifying element contained 7.49weight % of the P7 and P6 porous particles, 0.0557 weight % of carbonblack, 0.0078 weight % of magenta pigment M and 0.111 g/m² of carbonblack on a dry weight basis. This foamed, opacifying element exhibitedan LBV of 5.3 for a dry opacifying layer dry coating weight of 199 g/m²,and a luminous reflectance value of 52, and it also exhibited a magentatinted appearance that was reflected in the a* value of 1.19 and b*value of −1.31.

Foamed, Opacifying Element 6:

A foamable aqueous composition was prepared with 868.9 grams ofEAGLEBAN® FRC-0307 Drapery Compound and 131.12 grams of a 49.25 weight %aqueous dispersion of the P7 porous particles. This composition wasfoamed (aerated) and the resulting foamed aqueous composition was coatedonto a surface of the porous substrate described above with a coatingknife with a 1.52 mm (0.060 inch) gap. The dry foamed composition of thefoamed, opacifying element contained 11.91 weight % of the P7 porousparticles, 0.0989 weight % of carbon black, and 0.165 g/m² of carbonblack on a dry weight basis. This foamed, opacifying element exhibitedan LBV of 6.2 that increased the opacifying ability of the thinner dryopacifying layer dry coating weight of 167 g/m² and the luminousreflectance value was 43.

Foamed, Opacifying Element 7:

A foamable aqueous composition was prepared with 881 grams of EAGLEBAN®FRC-0307 Drapery Compound, 114.1 grams of a 49.25 weight % aqueousdispersion of the P7 porous particles, and 4.91 grams of a 51.1 weight %dispersion of the P4 porous particles. This composition was foamed(aerated) and the resulting foamed aqueous composition was coated onto asurface of the porous substrate described above with a coating knifewith a 1.52 mm (0.060 inch) gap. The dry foamed composition (dryopacifying layer) in the foamed, opacifying element contained 10.81weight % of the P7 and the P4 porous particles, 0.0859 weight % ofcarbon black, 0.0231 weight % of yellow tinting colorant Y2, and 0.161g/m² of carbon black on a dry weight basis. This foamed, opacifyingelement exhibited a very high LBV of 6.7 and increased opacifyingability of the dry opacifying layer dry coating weight of 188 g/m². Theluminous reflectance value measured for this foamed, opacifying elementwas 44 and the measured b* value of 0.46 reflects the presence of theyellow tinting colorant.

Predicted vs. Measured Light Blocking Values of Foamed, OpacifyingElements 8-12:

A suitable chosen foamable aqueous composition similar to thosedescribed for the foamed, opacifying elements described above wasprepared, foamed (aerated) and coated onto the a first supporting sideof porous substrate (A) having a known light blocking value LBV_(S), atvarious dry coating weights (in g/m²). The actual coating weight andlight blocking value (LBV_(T)) of each resulting foamed, opacifyingelement thus obtained was then measured, and the respective LBV_(T-S)values were calculated. These coating weights were then plotted againstthe respective LBV_(T-S) and the mathematical formula in the form of thebest fit equation was determined using regression analysis. This plotand equation were used to predict the coating weights required forvarious LBV_(T) values on a different porous substrate (B) of adifferent, color, basis weight, weave, and opacity, using the samechosen foamable aqueous composition as was applied to porous substrateA. The results are shown below in TABLE III.

Foamed opacifying elements 8-12 were prepared by foaming (aerating) andcoating onto the a first supporting side of porous substrate B, thechosen foamable aqueous composition at dry coating weights (in g/m²)predicted for various LBV_(T) values using the mathematical formulaobtained from the foamed, opacifying elements created using poroussubstrate A. As the data in TABLE III show, the average error in theprediction of dry coating weights for the desired LBV_(T) was less than5%, which is a very acceptable outcome.

TABLE III Foamed Dry LBV_(T-S) LBV_(T-S) Error as % DifferenceOpacifying Coating LBV_(T) LBV_(S) Calculated Predicted [(Calc − Pred)/Element Weight (g/m²) Measured Measured (Calc) (Pred) Calc] × 100  81.21 2.46 1 1.46 1.39 4.79  9 2.31 3.71 1 2.71 2.61 3.69 10 3.51 4.85 13.85 3.84 0.26 11 4.60 5.96 1 4.96 4.87 1.81 12 5.83 7.13 1 6.13 5.933.26

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

1. A method for providing a foamed, opacifying element having a targetlight blocking value (LBV_(T)) and comprising a target porous substratehaving a first supporting side and an opposing second supporting side,the method comprising: choosing a target porous substrate; choosing atarget light blocking value (LBV_(T)); determining a light blockingvalue (LBV_(S)) of the target porous substrate; calculating LBV_(T-S) asa difference between LBV_(T) and LBV_(S); choosing a foamable aqueouscomposition; using a mathematical formula to obtain a dry coating weightfor a single dry opacifying layer derived from the chosen foamableaqueous composition; and using the dry coating weight to form the singledry opacifying layer as the only layer disposed on the first supportingside of the target porous substrate, such that the single dry opacifyinglayer has light blocking value that is equal to LBV_(T-S), +10%, whereinthe chosen foamable aqueous composition has at least 35% solids and upto and including 70% solids, and comprises: (a) at least 0.05 weight %and up to and including 15 weight % of porous particles, each porousparticle comprising a continuous polymeric phase and a first set ofdiscrete pores dispersed within the continuous polymeric phase, theporous particles having a mode particle size of at least 2 μm and up toand including 50 μm and a porosity of at least 20 volume % and up to andincluding 70 volume %, and the continuous polymeric phase having a glasstransition temperature greater than 80° C. and comprising a polymerhaving a viscosity of at least 80 centipoises and up to and including500 centipoises at a shear rate of 100 see in ethyl acetate at aconcentration of 20 weight % at 25° C., (b) at least 20 weight % of abinder material; (c) at least 0.0001 weight % of one or more additivescomprising at least one surfactant; (d) water; and (e) at least 0.001weight % of an opacifying colorant different from all of the one or more(c) additives, which opacifying colorant absorbs predeterminedelectromagnetic radiation, all amounts being based on the total weightof the chosen foamable aqueous composition, and wherein the chosenfoamable aqueous composition can be foamed to provide a foamed aqueouscomposition having a foam density of at least 0.1 g/cm³ and up to andincluding 0.5 g/cm³.
 2. The method of claim 1, wherein the foamed,opacifying element has a luminous reflectance that is greater than 40%as measured by the Y tristimulus value.
 3. The method of claim 1,wherein the target porous substrate comprises a porous textile web,porous polymer film, porous cellulosic material, porous ceramicmaterial, or porous glass material.
 4. The method of claim 1, whereinthe chosen foamable aqueous composition comprises a tinting colorant, aflame retardant, an antimicrobial agent, or a flocking agent as a (c)additive.
 5. The method of claim 1, wherein the continuous polymericphase comprises at least 70 weight %, based on the total polymer weightin the continuous polymeric phase, of one or more polymers derived fromone or more of cellulose acetate, cellulose butyrate, cellulose acetatebutyrate, and cellulose acetate propionate.
 6. The method of claim 1,wherein the opacifying colorant is a carbon black that is present in anamount of at least 0.003 weight % and up to and including 0.2 weight %,based on the total weight of the chosen foamable aqueous composition. 7.The method of claim 1, wherein the chosen foamable aqueous compositioncomprises at least 0.5 weight % and up to and including 10 weight % ofthe porous particles, based on the total weight of the chosen foamableaqueous composition, which porous particles have a mode particle size ofat least 3 μm and up to and including 30 μm.
 8. The method of claim 1,wherein the surfactant of the one or more (c) additives is a foamingagent and the one or more (c) additives further comprise a foamstabilizing agent.
 9. The method of claim 1, wherein the one or more (c)additives further comprise an optical brightener in an amount of atleast 0.01 weight % and up to and including 2 weight %, based on thetotal weight of the chosen foamable aqueous composition.
 10. The methodof claim 1, wherein the one or more (c) additives comprise two or morematerials selected from a foaming agent, a foam dispersing agent, atinting colorant, an optical brightener, a flame retardant, anantimicrobial agent, and an inorganic filler.
 11. The method of claim 1,wherein the one or more (c) additives comprise an antimicrobial agentcomprising silver metal, a silver-containing compound, copper metal, acopper-containing compound, or a mixture of any of these.
 12. A systemfor providing a foamed, opacifying element having a target lightblocking value (LBV_(T)), comprising: (A) a set of foamable aqueouscompositions, each of the foamable aqueous compositions independentlyhaving at least 35% solids and up to and including 70% solids, andindependently comprising: (a) at least 0.05 weight % and up to andincluding 15 weight % of porous particles, each porous particlecomprising a continuous polymeric phase and a first set of discretepores dispersed within the continuous polymeric phase, the porousparticles having a mode particle size of at least 2 and up to andincluding 50 μm and a porosity of at least 20 volume % and up to andincluding 70 volume %, and the continuous polymeric phase having a glasstransition temperature greater than 80° C. and comprising a polymerhaving a viscosity of at least 80 centipoises and up to and including500 centipoises at a shear rate of 100 see in ethyl acetate at aconcentration of 20 weight % at 25° C., (b) at least 20 weight % of abinder material; (c) at least 0.0001 weight % of one or more additivescomprising at least one surfactant; (d) water; and (e) at least 0.001weight % of an opacifying colorant different from all of the one or more(c) additives, which opacifying colorant absorbs predeterminedelectromagnetic radiation, all amounts being based on the total weightof the foamable aqueous composition, and wherein each of the foamableaqueous compositions can be foamed to provide a foamed aqueouscomposition having a foam density of at least 0.1 g/cm³ and up to andincluding 0.5 g/cm³; (B) a set of mathematical formulae associated withthe set of foamable aqueous compositions, wherein the set ofmathematical formulae relate coating weight of the respective foamableaqueous compositions to respective light blocking values; and (C) a dataprocessor configured to perform a method for generating the foamed,opacifying element having the target light blocking value (LBV_(T)), themethod comprising: choosing a target porous substrate having a firstsupporting side; choosing a target light blocking value (LVB_(T));determining a light blocking value (LBV_(S)) of the target poroussubstrate; calculating LBV_(T-S) as a difference between LBV_(T) andLBV_(S); choosing a foamable aqueous composition; using a mathematicalformula to obtain a dry coating weight for a single dry opacifying layerderived from the chosen foamable aqueous composition; and using the drycoating weight to form the single dry opacifying layer as the only layerdisposed on the first supporting side of the target porous substrate,such that the single dry opacifying layer has a light blocking valuethat is equal to LBV_(T-S), +10%.
 13. The system of claim 12, whereinchoosing the target porous substrate and determining the mathematicalformula for each of the foamable aqueous compositions are carried outusing economic aspects or aesthetics aspects.
 14. The system of claim12, wherein the continuous polymeric phase comprises one or morecellulose polymers.
 15. The system of claim 12, wherein the opacifyingcolorant is a carbon black that is present in an amount of at least0.003 weight % and up to and including 0.2 weight %, based on the totalweight of the chosen foamable aqueous composition.
 16. The system ofclaim 12, wherein the chosen foamable aqueous composition comprises atleast 0.5 weight % and up to and including 10 weight % of the porousparticles, based on the total weight of the chosen foamable aqueouscomposition, which porous particles have a mode particle size of atleast 3 μm and up to and including 30 μm.
 17. The system of claim 12,wherein the one or more (c) additives further comprise metal flakes thatare present within the porous particles.
 18. The system of claim 12,wherein the at least one surfactant of the one or more (c) additives isa foaming agent and the one or more (c) additives further comprise afoam stabilizing agent.
 19. The system of claim 12, wherein the one ormore (c) additives further comprise an optical brightener in an amountof at least 0.01 weight % and up to and including 2 weight %, based onthe total weight of the chosen foamable aqueous composition.
 20. Thesystem of claim 12, wherein the one or more (c) additives comprise anantimicrobial agent comprising silver metal, a silver-containingcompound, copper metal, a copper-containing compound, or a mixture ofany of these.